Students who feel difficulty in solving the problems can quickly understand the concepts with the help of our Big Ideas Math Book 1st Grade Answer Key Chapter 8 Add and Subtract Tens. We provide the step by step explanations for all the questions by using the figures. You can easily understand the concepts in-depth with the help of the Big Ideas Math Answers Grade 1 Chapter 8 Add and Subtract Tens.

In order to excel in the exam, we suggest the students of 1st standard refer to the Big Ideas Math Book 1st Grade Answer Key Chapter 8 Add and Subtract Tens. With the help of Big Ideas Math Answers Grade 1 Chapter 8 Add and Subtract Tens you can score the best marks in the exams. Hit the links and start solving the problems using simple methods.

Vocabulary

Lesson: 1 Mental Math: 10 More

Lesson: 2 Mental Math: 10 Less

Lesson: 4 Add Tens Using a Number Line

Lesson: 5 Subtract Tens

Lesson: 6 Subtract Tens Using a Number Line

Lesson: 7 Use Addition to Subtract Tens

Lesson: 8 Add Tens to a Number

Chapter: 8 Add and Subtract Tens

### Add and Subtract Tens Vocabulary

Organize It

Review Words:
digits

Use the review words to complete the graphic organizer.

The ____________ of 16 are 1 and 6.

The digits of 16 Are 1 and 6.

Explanation:
10, 20, 30, 40 and so on are decade numbers.
Any of the numerals from 0 to 9, especially when forming part of a number are called as digits.

Define It

What am I?

Explanation:
13 – 3 = 10= BÂ  Â  Â  Â  Â  Â  Â  Â  Â  4 + 4 = 8 = P
5 + 1 = 6 = OÂ  Â  Â  Â  Â  Â  Â  Â  Â  Â 3 + 2 = 5 = L
5 + 4 = 9 = IÂ  Â  Â  Â  Â  Â  Â  Â  Â  Â  12 – 8 = 4 = R
6 – 4 = 2 = MÂ  Â  Â  Â  Â  Â  Â  Â  Â  Â 10 – 3 = U
1 + 2 = 3 = E
9 – 8 = 1 = N
Hence , YOU are open number line.

### Lesson 8.1 Mental Math: 10 More

Explore and Grow

Find each sum. What do you notice?

13 + 10 = __________

39 + 10 = __________

52 + 10 = __________

13 + 10 = 23
39 + 10 = 49
52 + 10 = 62

Explanation:
Addition is bringing two or more numbers (or things) together to make a new total.
1. Here, 13 and 10 are addends.
13 + 10 = 23.
2. Here, 39 and 10 are addends.
39 + 10 = 49.
3. Here, 52 and 10 are addends.
52 + 10 = 62.
Hence, its noticed that total number of groups are 10 in all the counters.

Show and Grow

Use mental math.

Question 1.
14 + 10 = __________
14 + 10 = 24

Explanation:
Here, 14 and 10 are addends.
14 + 10 = 24.
Hence, Sum = 24.

Question 2.
46 + 10 = __________
46 + 10 =56.

Explanation:
Here, 46 and 10 are addends.
46 + 10 = 56.
Hence, Sum = 56.

Question 3.
83 + 10 = __________
83 + 10 = 93.

Explanation:
Here, 83 and 10 are addends.
83 + 10 = 93.
Hence, Sum = 93.

Question 4.
75 + 10 = __________
75 + 10 = 85.

Explanation:
Here, 75 and 10 are addends.
75 + 10 = 85.
Hence, sum = 85.

Question 5.
21 + 10 = __________
21 + 10 = 31.

Explanation:
Here, 21 and 10 are addends.
21 + 10 = 31.
Hence, Sum = 31.

Question 6.
60 + 10 = __________
60 + 10 = 70.

Explanation:
Here, 60 and 10 are addends.
60 + 10 = 70.
Hence, Sum = 70.

Question 7.
10 + 89 = __________
10 + 89 = 99.

Explanation:
Here, 10 and 89 are addends.
10 + 89 = 99.
Hence, Sum = 99.

Question 8.
10 + 68 = __________
10 + 68 = 78.

Explanation:
Here, 10 and 68 are addends.
10 + 68 = 78.
Hence, Sum = 78.

Apply and Grow: Practice

Use Mental math.

Question 9.
16 + 10 = __________
16 + 10 = 26.

Explanation:
Here, 16 and 10 are addends.
16 + 10 = 26.
Hence, Sum = 26.

Question 10.
63 + 10 = __________
63 + 10 = 73.

Explanation:
Here, 63 and 10 are addends.
63 + 10 = 73.
Hence, Sum = 73.

Question 11.
8 + 10 = __________
8 + 10 = 18.

Explanation:
Here, 8 and 10 are addends.
8 + 10 = 18.
Hence, Sum = 18.

Question 12.
44 + 10 = __________
44 + 10 = 54.

Explanation:
Here, 44 and 10 are addends.
44 + 10 = 54.
Hence, Sum = 54.

Question 13.
19 + 10 = __________
19 + 10 = 29.

Explanation:
Here, 19 and 10 are addends.
19 + 10 = 29.
Hence, Sum = 29.

Question 14.
59 + 10 = __________
59 + 10 = 69.

Explanation:
Here, 59 and 10 are addends.
59 + 10 = 69.
Hence, Sum = 69.

Question 15.
10 + 22 = __________
10 + 22 = 32.

Explanation:
Here, 10 and 22 are addends.
10 + 22 = 32.
Hence, Sum = 32.

Question 16.
10 + 50 = __________
10 + 50 = 60.

Explanation:
Here, 10 and 50 are addends.
10 + 50 = 60.
Hence, Sum = 60.

Question 17.
10 + 71 = __________
10 + 71 = 81.

Explanation:
Here, 10 and 71 are addends.
10 + 71 = 81.
Hence, Sum = 81.

Question 18.
10 + 38 = __________
10 + 38 = 48.

Explanation:
Here, 10 and 38 are addends.
10 + 38 = 48.
Hence, Sum = 48.

Question 19.
55 + __________ = 65
55 + _10__ = 65

Explanation:
Here, 55 and Missing number are addends.
Sum is given = 65
Let the missing number be X.
55 + X= 65
X = 65 – 55
X = 10.
Hence, equation is Â 55 + 10 = 65.

Question 20.
87 + __________ = 97
87 + __10__ = 97

Explanation:
Here, 87 and Missing number are addends.
Sum is given = 97
Let the missing number be X.
87 + X = 97
X = 97 – 87
X = 10.
Hence, equation is 87 + 10 = 97.

Question 21.
DIG DEEPER!
Use each number once to complete the equations.
86Â  Â  Â  Â 76Â  Â  Â  Â 10Â  Â  Â  Â  Â 66
_________ + 10 = __________Â  Â  Â  Â  Â  Â  Â  ___________ + __________ = 96
66 + 10 = 76
86 + 10 = 96

Explanation:
1.Â  _________ + 10 = __________
We know among two addends, one is 10.
2. Â  Â  ___________ + __________ = 96
Given numbers 86,76,10,66.
Place every given number next to given addend 10:
86 + 10 = 96
76 + 10 = 86
10 + 10 = 20
66 + 10 =76.
Among this equations, for the first equation isÂ  66 + 10 =76.
and the secondÂ  is 86 + 10 = 96 because theÂ  it fulfills the given condition. (Use each number once to complete the equations.)

Think and Grow: Modeling Real Life

There are 33 students on a bus. 10 more get on. How many students are on the bus now?

___________ students

Total number of students on the bus now = 43.
Given:
Number of students in a bus = 33
Number of students more got into the bus = 10

Explanation:
Total number of students on the bus now = Number of students in a bus + Number of students more get into the bus = 33 + 10
= 43.
Hence, Total number of students on the bus now = 43.

Show and Grow

Question 22.
There are 61 tents at a campground. 10 more are put up. How many tents are at the campground now?

____________ tents

Number of tents at the campground now = 71.

Given:
Number of tents at a campground =61
Number of tents more put up at the campground= 10

Explanation:
Number of tents at the campground now = Number of tents at a campground – Number of tents more put up at the campground
= 61 + 10
= 71
Hence, Number of tents at the campground now = 71.

### Mental Math: 10 More Practice 8.1

Use Mental math.

Question 1.
30 + 10 = __________
30 + 10 = 40

Explanation:
Here, 30 and 10 are addends.
30 + 10 = 40
Hence, Sum = 40.

Question 2.
81 + 10 = __________
81 + 10 = 91

Explanation:
Here, 81 and 10 are addends.
81 + 10 = 91.
Hence, Sum = 91.

Question 3.
6 + 10 = __________
6 + 10 = 16

Explanation:
Here, 6 and 10 are addends.
6 + 10 = 16.
Hence, Sum = 16.

Question 4.
57 + 10 = __________
57 + 10 = 67

Explanation:
Here, 57 and 10 are addends.
57 + 10 = 67.
Hence, Sum = 67.

Question 5.
48 + 10 = __________
48 + 10 = 58.

Explanation:
Here, 48 and 10 are addends.
48 + 10 = 58.
Hence, Sum = 58.

Question 6.
26 + 10 = __________
26 + 10 = 36.

Explanation:
Here, 26 and 10 are addends.
26 + 10 = 36.
Hence, Sum = 36.

Question 7.
10 + 43 = __________
10 + 43 = 53.

Explanation:
Here, 10 and 43 are addends.
10 + 43 = 53.
Hence, Sum = 53.

Question 8.
10 + 65 = __________
10 + 65 = 75.

Explanation:
Here, 10 and 65 are addends.
10 + 65 = 75.
Hence, Sum = 75.

Question 9.
10 + 82 = __________
10 + 82 = 92.

Explanation:
Here, 10 and 82 are addends.
10 + 82 = 92.
Hence, Sum = 92.

Question 10.
10 + 79 = __________
10 + 79 = 89.

Explanation:
Here, 10 and 79 are addends.
10 + 79 = 89.
Hence, Sum = 89.

Question 11.
22 + __________ = 32
22 + 10 =32.

Explanation:
Here, 22 and Missing number are addends.
Let the missing number be X.
Sum is given =32
22 + X = 32
X = 32 – 22
X = 10.
Hence, equation is 22 + 10 =32.

Question 12.
85 + __________ = 95
85 + 10 = 95.

Explanation:
Here, 85 and Missing number are addends.
Let the missing number be X.
Sum is given = 95
85 + X = 95
X = 95 – 85
X = 10.
Hence, equation is 85 + 10 = 95.

Question 13.
64 + __________ = 74
64 + 10 = 74.

Explanation:
Here, 64 and Missing number are addends.
Let the missing number be X.
Sum is given = 74.
64 + X = 74
X = 74 – 64
X = 10.
Hence, equationÂ  is 64 + 10 = 74.

Question 14.
41 + __________ = 51
41 + 10 = 51.

Here, 41 and Missing number are addends.
Let the missing number be X.
Sum is given = 51.
41 + X = 51
X = 51 – 41
X = 10.
Hence, equation is 41 + 10 = 51 .

Question 15.
DIG DEEPER!
Use each number once to complete the equations.
25Â  Â  Â  Â  10Â  Â  Â  Â 15Â  Â  Â  Â 35
10 + __________ = _________Â  Â  Â  Â  Â  Â  Â  25 + __________ = ___________
10 + 15 = 25
25 +10 = 35

Explanation:
1. 10 + __________ = _________
2. 25 + __________ = ___________
Given numbers 25,10,15,35 are other addends.
Check out placing each addend next to 10.
Equation are ,
10 + 25 = 35
10 + 10 = 20
10 + 15 = 25
10 + 35 =45.
Among this equations, for the first equation is 10 + 15 = 25
and the secondÂ  is 25 + 10 = 35 because theÂ  it fulfills the given condition .(Use each number once to complete the equations.)

Question 16.
Modeling Real Life
There are 142 teachers at a school. The school hires 10 more. How many teachers are there now?

_____________ teachers
Number of teachers are there now = 152.

Given:
Number of teachers at a school = 142
Number of teachers the school hired more = 10

Explanation:
Number of teachers are there now = Number of teachers at a school + Number of teachers the school hired more
= 142 + 10
= 152.
Hence, Number of teachers are there now = 152.

Review & Refresh

Question 17.

10 less than 87 is _________ .
87 – 10 = 77.

Explanation:
There are 87 mangoes in aÂ  basket.
10 mangoes got spoiled. How many mangoes left??
Subtract the mangoes
87 – 10 = 77.
Hence, equation is 87 – 10 = 77.

Question 18.

1 less than 33 is __________ .
33 – 1 = 32

Explanation:
There are 33 mangoes in aÂ  basket.
1 mango got spoiled. How many mangoes left??
Subtract the mangoes
33 – 1 = 32.
Hence, equation is 33 – 1 = 32.

### Lesson 8.2 Mental Math: 10 Less

Explore and Grow

Find each difference. What do you notice?

33 – 10 = __________

67 – 10 = __________

82 – 10 = __________
33Â  -10 = 23
67 – 10 = 57
82 – 10 = 72

Explanation:
1. The number that is to be subtracted from is called Minuend.
The number that is to be subtracted is called Subtrahend:
The result of subtracting one number from another is called Difference:
In this case, 33 is minuend and 10 is subtrahend.
Now subtract this two:
=> 33Â  -10 = 23
Hence, difference is Â 23.
2. In this case, 67 is minuend and 10 is subtrahend.
Now subtract this two:
=> 67 – 10 = 57
Hence, difference is 57.
3. In this case, 82 is minuend and 10 is subtrahend.
Now subtract this two:
=> 82 – 10 = 72
Hence, difference is 72.

Show and Grow

Use mental math.

Question 1.
55 – 10 = __________
55 – 10 = 45

Explanation:
In this case, 55 is minuend and 10 is subtrahend.
Now subtract this two:
55 – 10 = 45
Hence, Difference = 45.

Question 2.
21 – 10 = __________
21 – 10 = 11

Explanation:
In this case, 21 is minuend and 10 is subtrahend.
Now subtract this two:
21 – 10 = 11
Hence, Difference = 11.

Question 3.
18 – 10 = __________
18 – 10 =8.

Explanation:
In this case, 18 is minuend and 10 is subtrahend.
Now subtract this two:
18 – 10 =8.
Hence, Difference = 8.

Question 4.
74 – 10 = __________
74 – 10 = 64.

Explanation:
In this case, 74 is minuend and 10 is subtrahend.
Now subtract this two:
74 – 10 = 64.
Hence, Difference = 64.

Question 5.
89 – 10 = __________
89 – 10 = 79.

Explanation:
In this case, 89 is minuend and 10 is subtrahend.
Now subtract this two:
89 – 10 = 79.
Hence, Difference = 79.

Question 6.
72 – 10 = __________
72 – 10 = 62.

Explanation:
In this case, 72 is minuend and 10 is subtrahend.
Now subtract this two:
72 – 10 = 62.
Hence, Difference = 62.

Apply and Grow: Practice

Use mental math

Question 7.
60 – 10 = __________
60 – 10 = 50.

Explanation:
In this case, 60 is minuend and 10 is subtrahend.
Now subtract this two:
60 – 10 = 50.
Hence, Difference = 50.

Question 8.
45 – 10 = __________
45 – 10 = 35

Explanation:
In this case, 45 is minuend and 10 is subtrahend.
Now subtract this two:
45 – 10 = 35
Hence, Difference = 35.

Question 9.
50 – 10 = __________
50 – 10 = 40

Explanation:
In this case, 50 is minuend and 10 is subtrahend.
Now subtract this two:
50 – 10 = 40
Hence, Difference = 40.

Question 10.
34 – 10 = __________
34 – 10 = 24

Explanation:
In this case, 34 is minuend and 10 is subtrahend.
Now subtract this two:
34 – 10 = 24
Hence, Difference = 24.

Question 11.
51 – 10 = __________
51 – 10 = 41

Explanation:
In this case, 51 is minuend and 10 is subtrahend.
Now subtract this two:
51 – 10 = 41
Hence, Difference = 41.

Question 12.
86 – 10 = __________
86 – 10 = 76.

Explanation:
In this case, 86 is minuend and 10 is subtrahend.
Now subtract this two:
86 – 10 = 76.
Hence, Difference = 76.

Question 13.
64 – 10 = __________
64 – 10 = 54.

Explanation:
In this case, 64 is minuend and 10 is subtrahend.
Now subtract this two:
64 – 10 = 54.
Hence, Difference = 54.

Question 14.
97 – 10 = __________
97 – 10 = 87.

Explanation:
In this case, 97 is minuend and 10 is subtrahend.
Now subtract this two:
97 – 10 = 87.
Hence, Difference = 87.

Question 15.
28 – 10 = __________
28 – 10 = 18.

Explanation:
In this case, 28 is minuend and 10 is subtrahend.
Now subtract this two:
28 – 10 = 18.
Hence, Difference = 18.

Question 16.
73 – 10 = __________
73 – 10 = 63.

Explanation:
In this case, 73 is minuend and 10 is subtrahend.
Now subtract this two:
73 – 10 = 63.
Hence, Difference = 63.

Question 17.
__________ – 10 = 22
32 – 10 = 22.

Explanation:
In this case, Missing number is minuend and 10 is subtrahend.
Let missing number be X.
Sum is given = 22
Now subtract:
X – 10 = 80
X = 22 + 10
X = 32.
Hence, Equation = 32 – 10 = 22 .

Question 18.
__________ – 10 = 80
90 – 10 = 80.

Explanation:
In this case, Missing number is minuend and 10 is subtrahend.
Let missing number be X.
Sum is given = 80.
Now subtract :
X – 10 = 80
X = 80 + 10
X = 90.
Hence, Equation = 90 – 10 = 80.

Question 19.
YOU BE THE TEACHER
Is Newton correct? Explain.

94 – 10 = 84.

Explanation:
In this case, 94 is minuend and 10 is subtrahend.
Now subtract this two:
94 – 10 = 84.
Hence, Difference = 84.
Therefore, Newton is correct.

Think and Grow: Modeling Real Life

You want to ride all 47 rides at an amusement park. You ride 10 of them. How many rides are left?

Subtraction equation:

_________ rides.

Number of rides left = 37.

Given:
Total number of rides you want to ride at an amusement park = 47
Number of rides you have taken out of them = 10

Explanation:
Number of rides left = Total number of rides you want to ride at an amusement park – Number of rides you have taken out of them
= 47 – 10
= 37.
Hence, Number of rides left = 37.

Show and Grow

Question 20.
You want to try all 65 flavors at a frozen yogurt shop. You try 10 of them. How many flavors are left?

Subtraction equation:

_________ flavors.

Number of flavors left = 55.

Given:
Total number of flavors you want to try at a frozen yogurt shop = 65
Number of flavors you have tried out of them = 10

Explanation:
Number of flavors left = Total number of flavors you want to try at a frozen yogurt shop – Number of flavors you have tried out of them
= 65 – 10
= 55
Hence,Â  Number of flavors left = 55.

### Mental Math: 10 Less Practice 8.2

Use mental math.

Question 1.
12 – 10 = __________
12 – 10 = 2.

Explanation:
In this case, 12 is minuend and 10 is subtrahend.
Now subtract this two:
12 – 10 = 2.
Hence, Difference = 2.

Question 2.
49 – 10 = __________
49 – 10 = 39.

Explanation:
In this case, 49 is minuend and 10 is subtrahend.
Now subtract this two:
49 – 10 = 39.
Hence, Difference = 39.

Question 3.
37 – 10 = __________
37 – 10 = 27.

Explanation:
In this case, 37 is minuend and 10 is subtrahend.
Now subtract this two:
37 – 10 = 27.
Hence, Difference = 27.

Question 4.
26 – 10 = __________
26 – 10 = 16.

Explanation:
In this case, 26 is minuend and 10 is subtrahend.
Now subtract this two:
26 – 10 = 16.
Hence, Difference = 16.

Question 5.
40 – 10 = __________
40 – 10 = 30.

Explanation:
In this case, 40 is minuend and 10 is subtrahend.
Now subtract this two:
40 – 10 = 30.
Hence, Difference = 30.

Question 6.
62 – 10 = __________
62 – 10 = 52.

Explanation:
In this case, 62 is minuend and 10 is subtrahend.
Now subtract this two:
62 – 10 = 52
Hence, Difference = 52.

Question 7.
88 – 10 = __________
88 – 10 = 78.

Explanation:
In this case, 88 is minuend and 10 is subtrahend.
Now subtract this two:
88 – 10 = 78.
Hence, Difference =78.

Question 8.
91 – 10 = __________
91 – 10 = 81.

Explanation:
In this case, 91 is minuend and 10 is subtrahend.
Now subtract this two:
91 – 10 = 81.
Hence, Difference = 81.

Question 9.
54 – 10 = __________
54 – 10 = 44

Explanation:
In this case, 54 is minuend and 10 is subtrahend.
Now subtract this two:
54 – 10 = 44.
Hence, Difference = 44.

Question 10.
76 – 10 = __________
76 – 10 = 66.

Explanation:
In this case, 76 is minuend and 10 is subtrahend.
Now subtract this two:
76 – 10 = 66.
Hence, Difference = 66.

Question 11.
__________ – 10 = 15
25 – 10 = 15

Explanation:
In this case, Missing numberÂ  is minuend and 10 is subtrahend.
Let missing number be X.
Sum is given = 15.
Now subtract :
X – 10 = 15
X = 15 + 10
X = 25.
Hence, Equation is 25 – 10 = 15.

Question 12.
__________ – 10 = 77
87 – 10 = 77

Explanation:
In this case, Missing number is minuend and 10 is subtrahend.
Let missing number be X.
Sum is given = 77.
Now subtract :
X – 10 = 77
X = 77 + 10
X = 87.
Hence, Equation is 87 – 10 = 77.

Question 13.
__________ – 10 = 34
44 – 10 = 34

Explanation:
In this case, Missing number is minuend and 10 is subtrahend.
Let missing number be X.
Sum is given = 34.
Now subtract :
X – 10 = 34
X = 34 + 10
X = 44.
Hence, Equation is 44 – 10 = 34.

Question 14.
__________ – 10 = 53
63 – 10 = 53.

Explanation:
In this case, Missing number is minuend and 10 is subtrahend.
Let missing number be X.
Sum is given = 53.
Now subtract :
X – 10 = 53
X = 53 + 10
X = 63.
Hence, Equation is 63 – 10 = 53.

Question 15.
YOU BE THE TEACHER
Is Descartes correct? Explain.

40 – 10 = 30

Explanation:
In this case, 40 is minuend and 10 is subtrahend.
Now subtract this two:
40 – 10 = 30.
Difference = 30.
Therefore, Descartes answer 50 is incorrect because he did not subtract the numbers instead he added the number.

Question 16.
Modeling Real Life
There are 99 levels in a video game. You complete 10 of them. How many are left?

____________ levels

Number of games left = 89.

Given:
Total number of levels in a video game = 99
Number of games I have completed out of them = 10

Explanation:
Number of games left = Total number of levels in a video game – Number of games I have completed out of them
= 99 – 10
= 89
Hence, Number of games left = 89.

Review & Refresh

Question 17.
A group of students are at the arcade. 4 of them leave. There are 5 left. How many students were there to start?

________ students

Total number of students were there to start = 9.

Given:
Number of students leave = 4
Number of students left = 5

Explanation:
Total number of students were there to start = Number of students leave + Number of students left
= 4 + 5
= 9
Hence, total number of students were there to start = 9.

Explore and Grow

Model each problem. How are the problems alike? How are they different?

3 + 2 = _______

30 + 20 = _______
3 + 2 = 5.
30 + 20 = 50.

Explanation:
A number that is added to another number is known as an addend.
1. In this case, 3 and 2 are the addends.
Sum is the result of adding two numbers.
3 + 2 = 5.
2. In this case, 30 and 20 are the addends.
Sum is the result of adding two numbers.
30 + 20 = 50.
Hence, the problem is alike in its addition process and different in its sum.

Show and Grow

Question 1.
40 + 50 = ?
____________ tens + ____________ tens = ____________ tens
So, 40 + 50 = ____________ .

40 + 50 = 90.

Explanation:
Place valueÂ is theÂ value of each digit in a number.
4 value in 40 = 4 tens
5 value in 50 = 5 tens
=> 4 tens + 5 tens = 9 tens.
So, 40 + 50 = 90.

Question 2.
30 + 30 = ?
____________ tens + ____________ tens = ____________ tens
So, 30 + 30 = ____________ .

30 + 30 = 60.

Explanation:
Place valueÂ is theÂ value of each digit in a number.
3 value in 30 = 3 tens
3 value in 30 = 3 tens
3 tens + 3 tens = 6 tens
So, 30 + 30 = 60.

Apply and Grow: Practice

Question 3.
20 + 40 = ?
____________ tens + ____________ tens = ____________ tens
So, 20 + 40 = ____________ .
20 + 40 = 60

Explanation:
Place valueÂ is theÂ value of each digit in a number.
2 value in 20 = 2 tens
4 value in 40 = 4 tens
2 tens + 4 tens = 6 tens
So, 20 + 40 = 60.

Question 4.
50 + 30 = ?
____________ tens + ____________ tens = ____________ tens
So, 50 + 30 = ____________ .
50 + 30 = 80.

Explanation:
Place valueÂ is theÂ value of each digit in a number.
5 value in 50 = 5 tens
3 value in 30 = 3 tens
5 tens + 3 tens = 8 tens
So, 50 + 30 = 80.

Question 5.
40 + 10 = _________
40 + 10 = 50.

Explanation:
Place valueÂ is theÂ value of each digit in a number.
4 value in 40 = 4 tens
1 value in 10 = 1 tens
4 tens + 1 tens = 5 tens
So, 40 + 10 = 50.

Question 6.
70 + 20 = _________
70 + 20 = 90.

Explanation:
Place valueÂ is theÂ value of each digit in a number.
7 value in 70 = 7 tens
2 value in 20 = 2 tens
7 tens + 2 tens = 9 tens
So, 70 + 20 = 90..

Question 7.
30 + 40 = _________
30 + 40 = 70.

Explanation:
Place valueÂ is theÂ value of each digit in a number.
3 value in 30 = 3 tens
4 value in 40 = 4 tens
3 tens + 4 tens = 7 tens
So, 30 + 40 = 70.

Question 8.
20 + 60 = __________
20 + 60 = 80.

Explanation:
Place valueÂ is theÂ value of each digit in a number.
2 value in 20 = 2 tens
6 value in 60 = 6 tens
2 tens + 6 tens = 8 tens
So, 20 + 60 = 80.

Question 9.
_________ + 10 = 40
30 + 10 = 40.

Explanation:
Let the first addend be X.
Sum is given = 40
X + 10 = 40
X = 40 – 10
x = 30.
Hence, Equation is 30 + 10 = 40.

Question 10.
_________ + 60 = 90
30 + 60 = 90.

Explanation:
Let the first addend be X.
Sum is given = 90
X + 60 = 90
X = 90 – 60
X = 30.
Hence, Equation is 30 + 60 = 90.

Question 11.
DIG DEEPER!
Which choices match the model?

50Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â 20 + 30
2 tens + 3 onesÂ  Â  Â  Â  Â  Â  Â  Â  Â  1 ten + 4 tens

1 ten + 4 tens = 5 tens.

Explanation:
In the above picture, 5 lines are given.
Considered each line value as 10.
Here, two addends are given in each choice:
1. 50
2. 20 + 30 = 50
3. 2 tens + 3 ones = 20 + 3=23
4. 1 ten + 4 tens = 5 tens
Hence, 4th choice matches the model because five lines of each value 10 = 50 not others as addition of two numbers it did not refer in the model.

Think and Grow: Modeling Real Life

One tray has 20 meatballs. Another tray has the same number of meatballs. How many meatballs are there in all?

Model:

__________ meatballs

Total number of meatballs are there in all = 40.

Given:
Number of meatballs one tray has = 20
Number of meatballs same another tray has = 20
Explanation:
Total number of meatballs are there in all =Â  Number of meatballs one tray has – Number of meatballs same another tray has
= 20 + 20
= 40
Hence, Total number of meatballs are there in all = 40.

Show and Grow

Question 12.
One box has 40 bags of pretzels. Another box has the same number of bags. How many bags are there in all?

Model:

__________ bags

Total number of bags are there in all = 80.

Given:
Number of bags of pretzels one box has = 40
Number of bags of pretzels another box has = 40

Explanation:
Total number of bags are there in all = Number of bags of pretzels one box has + Number of bags of pretzels another box has
= 40 + 40
= 80.
Hence, Total number of bags are there in all = 80.

Question 1.
20 + 70 = ?
____________ tens + ____________ tens = ____________ tens
So, 20 + 70 = ____________ .
2tens + 7tens = 9tens
20 + 70 = 90.

Explanation:
Here place value of 2 and 7 are considered.
2tens + 7tens = 9tens
20 + 70 =Â 90.

Question 2.
50 + 30 = ?
____________ tens + ____________ tens = ____________ tens
So, 50 + 30 = ____________ .
5tens + 3tens = 8tens
50 + 30 = 80.

Explanation:
Here place value of 2 and 7 are considered.
5tens + 3tens = 8tens
50 + 30 = 80.

Question 3.
60 + 20 = ___________
6tens + 2tens = 8tens.
60 + 20 = 80.

Explanation:
Here place value of 2 and 7 are considered.
6tens + 2tens = 8tens.
60 + 20 = 80.

Question 4.
40 + 40 = ____________
4tens + 4tens = 8tens.
40 + 40 = 80.

Explanation:
Here place value of 4 and 4 are considered.
4tens + 4tens = 8tens.
40 + 40 = 80.

Question 5.
__________ + 40 = 50
1 tens + 4 tens = 5 tens.
10 + 40 = 50.

Explanation:
Let the missing number be X.
X + 40 = 50
X = 50 – 40
X = 10
1 tens + 4 tens = 5 tens.
10 + 40 = 50.

Question 6.
___________ + 30 = 60
3 tens + 3 tens = 6 tens.
30 + 30 = 60.

Explanation:
Let the missing number be X.
X + 30 = 60
X = 60 – 30
X = 30
3 tens + 3 tens = 6 tens.
30 + 30 = 60.

Question 7.
___________ + 20 = 70
5 tens + 2 tens = 7 tens.
50 + 20 = 70.

Explanation:
Let the missing number be X.
X + 20 = 70
X = 70 – 20
X = 50
5 tens + 2 tens = 7 tens.
50 + 20 = 70.

Question 8.
_____________ + 50 = 90
5 tens + 4 tens = 90.
50 + 40 = 90.

Explanation:
Let the missing number be X.
X + 50 = 90
X = 90 – 50
X = 40
5 tens + 4 tens = 90.
50 + 40 = 90.

Question 9.
DIG DEEPER!
Which choices match the model?

3 tens + 4 onesÂ  Â  Â  Â  Â  Â  Â  Â  Â  Â 5 tens + 2 tens
60Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  30 + 40
3 tens + 4 tens = 7 tens
5 tens + 2 tens = 7 tens

Explanation:
1. 3 tens + 4 tens = 7 tens
2. 60
3. 5 tens + 2 tens = 7 tens
4. 30 + 40 = 70
Hence, 2nd and 3rd choice matches the model because five lines of each value 10Â  x 7 = 70 not others as addition of two numbers it did not refer in the model.

Question 10.
Modeling Real Life
One magic set has 30 pieces. Another set has the same number of pieces. How many pieces are there in all?

_____________ pieces
Total Number ofÂ  pieces are there in all = 60.

Explanation:
NumberÂ  of pieces magic sets has = 30
Number ofÂ  pieces another magic sets has sameÂ  = 30
Total Number ofÂ  pieces are there in all = NumberÂ  of pieces magic sets has + Number ofÂ  pieces another magic sets has same
= 30 + 30
= 60.
Hence, Total Number ofÂ  pieces are there in all = 60.

Review & Refresh

Question 11.
__________ = 6 + 5
11 = 6 + 5

Explanation:
Let the sum of addends 6 and 5 be X.
X = 6 + 5
X = 11.
Hence, 11 = 6 + 5.

Question 12.
__________ = 3 + 17
20 = 3 + 17

Explanation:
Let the sum of addends 3 and 17 be X.
X = 3 + 17
X = 20.
Hence, 20 = 3 + 17.

Question 13.
__________ = 11 + 5
16 = 11 + 5.

Explanation:
Let the sum of addends 11 and 5 be X.
X = 11 + 5
X = 16.
Hence, 16 = 11 + 5.

Question 14.
__________ = 5 + 9
14 = 5 + 9.

Explanation:
Let the sum of addends 5 and 9 be X.
X = 5 + 9
X = 14.
Hence, 14 = 5 + 9.

### Lesson 8.4 Add Tens Using a Number Line

Explore and Grow

30 + 20 = _________

30 + 20 = 50.

Explanation:
In math, a number line can be defined as a straight line with numbers placed at equal intervals or segments along its length.
Here, in the above picture the interval is calculated and added.

30 + 10 + 10
= 40 + 10
= 50 .
Hence, 30 + 20 = 50.

Show and Grow

Question 1.
50 + 40 = __________

50 + 40 = 90.

Explanation:
On the number line, give the interval of 10 for 4 timesÂ  and add them to given number.

Hence, 50 + 40 = 90.

Question 2.
60 + 20 = _____________

60 + 20 = 80

Explanation:
On the number line, give the interval of 10 for 2 times and add them to given number.

Hence, 60 + 20 = 80

Apply and Grow: Practice

Question 3.
40 + 20 = _________

40 + 20 = 60.

Explanation:
On the number line, give the interval of 10 for 2 times and add them to given number.

Hence, 40 + 20 = 60.

Question 4.
50 + 30 = ___________

50 + 30 = 80.

Explanation:
On the number line, give the interval of 10 for 3 times and add them to given number.

Hence, 50 + 30 = 80.

Question 5.
60 + 40 = __________

60 + 40 = 100.

Explanation:
On the number line, give the interval of 10 for 4 times and add them to given number.

Hence, 60 + 40 = 100.

Question 6.
20 + 50 = ___________

20 + 50 = 70.

Explanation:
On the number line, give the interval of 10 for 5 times and add them to given number.

Hence, 20 + 50 = 70.

Question 7.
MP Structure
Write an equation that matches the number line.

Equation: 70 + 10 +10 = 90.

Explanation:
On the number line, give the interval of 10 for 2 times and add them to given number.

Equation:
70 + 10 +10
= 80 + 10
= 90.
Hence, Equation: 70 + 10 +10 = 90.

Think and Grow: Modeling Real Life

You have 20 cans. You collect 20 more cans. Your friend collects 45 cans in all. Who collects more cans?

Model:

Compare: ___________ â—‹ ___________
Who collects more cans?Â  Â  Â  Â  Â  YouÂ  Â  Â  Â  Â  Friend

My friend collectsÂ  5 more cans than me .

Given:
Number of cans I have = 20
Number of cans I have collected more = 20

Explanation:
Total number of cans I have in all = Number of cans I have + Number of cans I have collected more
20 + 20 = 40.
Total number of cans my friend has = 45
Difference in cans collection = Total number of cans my friend has – Total number of cans I have in all
= 45 – 40
= 5

Comparison:

Hence, my friend collectsÂ  5 more cans than me .

Show and Grow

Question 8.
Your class makes 62 paper airplanes. Your friendâ€™s class makes 30 small airplanes and 30 large airplanes. Whose class makes more airplanes?

Model:

Compare: ___________ â—‹ ___________
Whose class makes more airplanes?
Your classÂ  Â  Â  Â  Â  Â  Â  Â  Â  Â Friend’s class

Total number of paper airplanes I make are 2 more than my friends paper making airplanes.

Given:
Total number of paper airplanes I make = 62
Number of paper small airplanes my friend’s class makes = 30
Number of paper large airplanes my friend’s class makesÂ  = 30

Explanation:
Total number of airplanes my friend’s class makes = Number of paper small airplanes my friend’s class makes + Number of paper large airplanes my friend’s class makes
= 30 + 30
= 60
Number of airplanes who makes more = Total number of paper airplanes class I makes – Total number of airplanes my friend’s class makes
=62 – 60
= 2

Comparison:

Hence, Total number of paper airplanes I makeÂ  2 more than my friends paper making airplanes.

### Add Tens Using a Number Line Practice 8.4

Question 1.
60 + 30 = __________

60 + 30 = 90.

Explanation:

Equation:
60+ 10 +10 +10
=70 + 10 +10
= 80 + 10
=90.

Question 2.
20 + 20 = __________

20 + 10+ 10 = 40.

Explanation:

Equation:
20 + 10+ 10
= 30 + 10
= 40.

Question 3.
30 + 70 = __________

30 + 70 = 100.

Explanation:

Equation:
30 + 10 + 10+ 10+ 10+ 10+ 10 +10
= 40 + 10+ 10+ 10+ 10+ 10 +10
= 50 +10+ 10+ 10+ 10 +10
= 60Â  +10+ 10+ 10 +10
= 70 + 10 + 10 +10
= 80 + 10 +10
= 90 + 10
= 100.

Question 4.
MP Structure
Write an equation that matches the number line.

Equation:
10 + 40 = 50.

Explanation:
The number line shows the interval of 10 for 4 times.
10 + 10 + 10 + 10 +10
= 20 + 10 + 10 + 10
= 30 + 10 + 10
= 40 + 10
= 50.

Question 5.
Modeling Real Life
You make 3 snow bricks. Your friend makes 20 small snow bricks and 30 large snow bricks. Who makes more snow bricks?

Who makes more snow bricks?Â  Â  Â  Â  Â  Â  Â  Â  YouÂ  Â  Â  Â  Â  Â  Â  Friend
My friend has 47 more snow bricks than me.

Given:
Total number of snow bricks I have made = 3
Number of small snow bricks my friend has made = 20
Number of large snow bricks my friend has made = 30

Explanation:
Total number of small and large snow bricks my friend has made = Number of small snow bricks my friend has made + Number of large snow bricks my friend has made
= 20 + 30
= 50
Number of Â snow bricks who makes more = Total number of small and large snow bricks my friend has made – total number of snow bricks I have made
= 50 – 3
= 47.

Comparison:

Hence, my friend has 47 more snow bricks than me.

Review & Refresh

Question 6.
Get to lo to subtract.
17 – 8 = ?

17 – __________ = 10
10 – __________ = __________
So, 17 – 8 = __________ .
17 – 8 = 9.

Given:
1. 17 – ____ = 10
Let the missing subtrahend be X.
Difference is given = 10
Subtract the numbers.
17 – X = 10
17 = 10 + X
17 – 10 = X
7 = X
Equation: 17 – 7 = 10.

### Lesson 8.5 Subtract Tens

Explore and Grow

Model each problem. How are the problems alike? How are they different?

5 – 2 = ___________

50 – 20 = ___________
5 – 2 = 3.
50 – 20 = 30.

Explanation:
Here, the minuend is 5 and the subtrahend is 2.
Now, Subtract the two numbers.
5 – 2 = 3.
Here, the minuend is 50 and the subtrahend is 20.
Now, Subtract the two numbers.
50 – 20 = 30.
Hence, the two equations are alike in the subtraction process yet different in the answers.

Show and Grow

Question 1.

70 – 30 = ?
____________ tens – ____________ tens = ____________ tens
So, 70 – 30 = ____________ .
7 tens – 3 tens = 4 tens
70 – 30 = 40.

Explanation:
Place valueÂ is theÂ value of each digit in a number.
7 value in 70 =7 tens
3 value in 30 = 3 tens
Subtract the two numbers:
7 tens – 3 tens = 4 tens
So, 70 – 30 = 40.

Question 2.
40 – 20 = __________
____________ tens – ____________ tens = ____________ tens
So, 40 – 20 = ____________ .
4 tens – 2 tens = 2 tens.
40 – 20 = 20.

Explanation:
Place valueÂ is theÂ value of each digit in a number.
4 value in 40 =4 tens
2 value in 20 = 2 tens
Subtract the two numbers:
4 tens – 2 tens = 2 tens.
So, 40 – 20 = 20.

Apply and Grow: Practice

Question 3.
90 – 30 = ?
____________ tens – ____________ tens = ____________ tens
So, 90 – 30 = ____________ .
9 tens – 3 tens = 6 tens.
90 – 30 = 60.

Explanation:
Place valueÂ is theÂ value of each digit in a number.
9 value in 90 =9 tens
3 value in 30 = 3 tens
Subtract the two numbers:
9 tens – 3 tens = 6 tens.
So, 90 – 30 = 60.

Question 4.
50 – 10 = ?
____________ tens – ____________ tens = ____________ tens
So, 50 – 10 = ____________ .
5 tens – 1 tens = 4 tens.
50 – 10 = 40.

Explanation:
Place valueÂ is theÂ value of each digit in a number.
5 value in 50 = 5 tens
1 value in 10 = 1 tens
Subtract the two numbers:
5 tens – 1 tens = 4 tens.
So, 50 – 10 = 40.

Question 5.
30 – 20 = __________
30 – 20 = 10.

Explanation:
Place valueÂ is theÂ value of each digit in a number.
3 value in 30 = 5 tens
2 value in 20 = 2 tens
Subtract the two numbers:
3 tens – 2 tens = 1 tens.
So, 30 – 20 = 10.

Question 6.
40 – 40 = __________
40 – 40 = 0.

Explanation:
Place valueÂ is theÂ value of each digit in a number.
4 value in 40 = 4 tens
4 value in 40 = 4 tens
Subtract the two numbers:
4 tens – 4 tens = 0 tens.
So, 40 – 40 = 0.

Question 7.
80 – 50 = __________
80 – 50 = 30.

Explanation:
Place valueÂ is theÂ value of each digit in a number.
8 value in 80 = 8 tens
5 value in 50 = 5 tens
Subtract the two numbers:
8 tens – 5 tens = 3 tens.
So, 80 – 50 = 30.

Question 8.
90 – 70 = ___________
90 – 70 = 20.

Explanation:
Place valueÂ is theÂ value of each digit in a number.
9 value in 90 = 9 tens
7 value in 70 = 7 tens
Subtract the two numbers:
9 tens – 7 tens = 2 tens.
So, 90 – 70 = 20.

Question 9.
20 – __________ = 10
20 – 10 = 10.

Explanation:
Here, the minuend is 20.
Difference is 10.
Let the subtrahend be X.
Now, subtract the numbers.
20 – X = 10.
20 = 10 + X
20 – 10 = X
10 = X.
Hence, 20 – 10 = 10.

Question 10.
50 – __________ = 20
50 – 30 = 20.

Explanation:
Here, the minuend is 50.
Difference is 20.
Let the subtrahend be X.
Now, subtract the numbers.
50 – X = 20.
50 = 20 + X
50 – 20 = X
30 = X.
Hence, 50 – 30 = 20.

Question 11.
DIG DEEPER!
Which choices match the model?

50 – 30Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â 80 – 30
5 tens – 3 tensÂ  Â  Â  Â  Â  Â  Â  Â  Â  Â 8 tens – 3 tens
8 tens – 3 tens = 5 tens.

Explanation:
In the given picture,Â  total there are eight lines.
Consider each line value is 10. Out of them 3 lines are removed.
=> 80 – 30 = 50.
2. 50 – 30 = 20
3. 5 tens – 3 tens = 2 tens.
4. 8 tens – 3 tens = 5 tens.
Hence, 4th equation is suitable for the model .

Think and Grow: Modeling Real Life

You have 80 math problems. You have 40 fewer spelling words. How many spelling words do you have?

Model:

Subtraction equation:

______________ spelling words

Number of spelling words I have = 40.

Explanation:
Total number of math problems I have = 80
Number of fewer spelling words = 40

Subtraction equation:
Number of spelling words do you have = Total number of math problems I have – Number of fewer spelling words
= 80 – 40
= 40.
Hence, Number of spelling words I have = 40.

Show and Grow

Question 12.
There are 60 students in a play. A football team has 30 fewer students. How many students are on the football team?
Model:

Subtraction equation:

______________ students

Number of students on the football team = 30.

Explanation:
Total number of students in a play = 60
Number of fewer students in a football team = 30

Subtraction equation:
Number of students on the football team = Total number of students in a play – Number of fewer students in a football team
= 60 – 30
= 30
Hence, Number of students on the football team = 30.

### Subtract Tens Practice 8.5

Question 1.
70 – 50 = ?
____________ tens – ____________ tens = ____________ tens
So, 70 – 50 = ____________ .
70 – 50 = 20.
7 tens – 5 tens = 2 tens.

Explanation:
Place valueÂ is theÂ value of each digit in a number.
7 value in 70 = 7 tens
5 value in 50 = 5 tens
Subtract the two numbers:
7 tens – 5 tens = 2 tens.
So, 70 – 50 = 20.

Question 2.
60 – 20 = ?
____________ tens – ____________ tens = ____________ tens
So, 60 – 20 = ____________ .
60 – 20 = 40.
6 tens – 2 tens = 4 tens.

Explanation:
Place valueÂ is theÂ value of each digit in a number.
6 value in 60 = 6 tens
2 value in 20 = 2 tens
Subtract the two numbers:
6 tens – 2 tens = 4 tens.
So, 60 – 20 = 40.

Question 3.
60 – 60 = __________
60 – 60 = 0.

Explanation:
Here, the minuend is 60 and subtrahend is 60.
Subtract the two numbers:
60 – 60 = 0.

Question 4.
30 – 10 = ____________
30 – 10 = 20.

Explanation:
Here, the minuend is 30 and subtrahend is 10.
Subtract the two numbers:
30 – 10 = 20.

Question 5.
70 – __________ = 0
70 – 70 =0.

Explanation:
Here, the minuend is 70.
Let the subtrahend be X
Difference = 0.
Subtract the two numbers:
70 – X = 0
70 = 0 + X
70 – 0 = X
70 = X
Equation is 70 – 70 =0.

Question 6.
50 – ___________ = 40
50 – 10 =40.

Explanation:
Here, the minuend is 50.
Let the subtrahend be X
Difference = 40.
Subtract the two numbers:
50 – X = 40
50 = 40 + X
50 – 40 = X
10 = X
Equation is 50 – 10 =40.

Question 7.
40 – ____________ = 20
40 – 20 = 20.

Explanation:
Here, the minuend is 40.
Let the subtrahend be X
Difference = 20.
Subtract the two numbers:
40 – X = 20
40 = 20 + X
40 – 20 = X
20 = X
Equation is 40 – 20 = 20.

Question 8.
90 – ____________ = 50
90 – 40 =50.

Explanation:
Here, the minuend is 90.
Let the subtrahend be X
Difference = 50.
Subtract the two numbers:
90 – X = 50
90 = 50 + X
90 – 50 = X
40 = X
Equation is 90 – 40 =50.

Question 9.
DIG DEEPER!
Which choices match the model?

9o – 50Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  40 – 50
4 tens – 5 onesÂ  Â  Â  Â  Â  Â  Â  9 tens – 5 tens
9 tens – 5 tens = 4 tens.

Explanation:
In the given picture,Â  total there are nine lines.
Consider each line value is 10. Out of them 5 lines are removed.
=> 9 tens – 5 tens = 4 tens
2. 90 – 50 = 40
3. 40 – 50 = -10
4. 4 tens – 5 ones = 40 + 5 = 45.
Hence, out of four choices, the first choice is correct for the model than other three equations.

Question 10.
Modeling Real Life
There are 40 chairs in the library. There are 30 fewer tables than chairs. How many tables are there?

___________ tables
Number of tables are there = 10.

Explanation:
Total number of chairs in a library = 40
Number of fewer tables than chairs = 30
Number of tables are there = Total number of chairs in a library – Number of fewer tables than chairs
= 40 – 30
= 10.
Hence, Number of tables are there = 10.

Review & Refresh

Question 11.
11 – 7 = ____________
11 – 7 = 4

Explanation:
Here, the minuend is 17 and subtrahend is 7.
Subtract the two numbers:
11 – 7 = 4
Hence, 11 – 7 = 4.

Question 12.
16 – 8 = ____________
16 – 8 = 8.

Explanation:
Here, the minuend is 16 and subtrahend is 8.
Subtract the two numbers:
16 – 8 = 8.
Hence, 16 – 8 = 8.

Question 13.
15 – 8 = ____________
15 – 8 = 7.

Explanation:
Here, the minuend is 15 and subtrahend is 8.
Subtract the two numbers:
15 – 8 = 7.
Hence, 15 – 8 = 7.

Question 14.
18 – 9 = ____________
18 – 9 = 9.

Explanation:
Here, the minuend is 18 and subtrahend is 9.
Subtract the two numbers:
18 – 9 = 9.
Hence, 18 – 9 = 9.

### Lesson 8.6 Subtract Tens Using a Number Line

Explore and Grow

40 – 20 = ___________

40 – 20 = 20.

Explanation:
In math, a number line can be defined as a straight line with numbers placed at equal intervals or segments along its length.
Here, we need to represent 20 subtracted from 40.

Show and Grow

Question 1.
80 – 50 = __________

80 – 50 = 30.

Explanation:
Here, we need to represent 50 subtracted from 80.

Question 2.
70 – 30 = ___________

70 – 30 = 40.

Explanation:
Here, we need to represent 30 subtracted from 70.

Apply and Grow: Practice

Question 3.
60 – 20 = __________

60 – 20 = 40.

Explanation:
Here, we need to represent 20 subtracted from 60.

Question 4.
40 – 30 = ____________

40 – 30 = 10.

Explanation:
Here, we need to represent 30 subtracted from 40.

Question 5.
90 – 40 = ____________

90 – 40 = 50.

Explanation:
Here, we need to represent 40 subtracted from 90.

Question 6.
90 – 70 = ____________

90 – 70 = 20.

Explanation:
Here, we need to represent 70 subtracted from 90.

Question 7.
MP Structure
Write the equation that matches the number line.

80 – 40 = 40

Explanation:
80 – 10 -10 – 10 -10
= 70 -10 – 10 -10
= 60 – 10 -10
= 50 -10
= 40.

Think and Grow: Modeling Real Life

You have a bucket of 80 golf balls. You hit 60 of them. Your friend has 28 golf balls left. Who has more golf balls left?

Model:

Subtraction equation:
Compare: __________ â—‹ ___________
Who has more golf balls left?Â  Â  Â  Â  Â  Â  Â  Â YouÂ  Â  Â  Â  Â  Â  Â  Â Friend
My friend has left 8 golf balls more than me.

Given:
Total number of golf balls I have = 80
Number of golf balls I hit out of them = 60
Explanation:
Number of gold balls I left = Total number of golf balls I have – Number of golf balls I hit out of them
= 80 – 60
= 20

Number of golf balls my friend left = 28
Comparison:
Number of golf balls who left more = Number of golf balls my friend left –Â  Number of gold balls I left
= 28 – 20
= 8.

Hence, my friend has left 8 golf balls more than me.

Show and Grow

Question 8.
Pack A has 50 batteries. 40 of them have been used. Pack B has 15 batteries. Which pack has more bafferies left?

Model:

Subtraction equation:
Compare: __________ â—‹ ___________
Who has more golf balls left?Â  Â  Â  Â  Â  Â  Â Pack AÂ  Â  Â  Â  Â  Â  Â  Pack B
5 batteries are left more in pack B than pack A.

Given:
Total number of batteries in pack A has= 50
Number of batteries used in pack A = 40
Total number of batteries in pack B has = 15
Explanation:
Number of batteries left in pack A = Total number of batteries in pack A has – Number of batteries used in pack A
= 50 – 40
= 10.

Comparison:
Number of batteries which pack has left more = Total number of batteries in pack B has – Number of batteries left in pack A
= 15 – 10
= 5

Hence,5 batteries are left more in pack B than pack A.

### Subtract Tens Using a Number Line Practice 8.6

Question 1.
50 – 30 = _____________

50 – 30 = 20.

Explanation:
Here, we need to represent 30 subtracted from 50.

Question 2.
80 – 60 = ____________

80 – 60 = 20.

Explanation:
Here, we need to represent 60 subtracted from 80.

Question 3.
90 – 20 = ____________

90 – 20 = 70.

Explanation:
Here, we need to represent 20 subtracted from 90.

Question 4.
MP Structure
Write the equation that matches the number line.

60 – 50 = 10.

Explanation:
Here we need to subtract 10 5times from 60.
60 – 10 -10 -10 -10 -10
= 50 -10 -10 -10 -10
=Â  40 – 10 -10 -10
= 30 – 10 -10
= 20 – 10
= 10.

Question 5.
Modeling Real Life
You have 80 raffle tickets and give away 30 of them. Your friend has 47 raffle tickets. Who has more raffle tickets?

Who has more raffle tickets? You Friend

I have 5 raffle tickets more than my friend.

Given:
Total number of raffle tickets = 80
Number of raffle tickets I gave away = 30
Explanation:
Number of raffle tickets I have now = Total number of raffle tickets – Number of raffle tickets I gave away
= 80 -30
= 50
Number of raffles tickets my friend has = 47

Comparison:
Number of raffle ticket who has more = Number of raffle tickets I have now – Number of raffles tickets my friend has
= 50 – 47
= 3
Hence, I have 5 raffle tickets more than my friend.

Review & Refresh

Question 6.
13 – 8 = ?
Think 8 + __________ = 13.
So, 13 – 8 = __________ .
13 – 8 = 5.

Explanation:
Think 8 + ____5______ = 13.
So, 13 – 8 = ___5_______ .

Question 7.
15 – 7 = ?
Think 7 + _________ = 15
So, 15 – 7 = ____________ .
15 – 7 = 8.

Explanation:
Think 7 + ____8_____ = 15
So, 15 – 7 = ______8______ .

### Lesson 8.7 Use Addition to Subtract Tens

Explore and Grow

Complete each equation. What do you notice?

20 + 50 = 70
50 – 20 = 30.

Explanation:
Here, for number 20 we are adding 5 times 10.

Here, we are subtracting 20 from number 50.

Show and Grow

Question 1.
90 – 70 = ?

Think 70 + _________ = 90
So, 90 – 70 = _________ .
90 – 70 = 20.

Explanation:

Think 70 + ____20_____ = 90
So, 90 – 70 = ___20______ .

Question 2.
60 – 30 = ?

Think 30 + _________ = 60
So, 60 – 30 = _________ .
60 – 30 = 30.

Explanation:

Think 30 + __30___ = 60
So, 60 – 30 =____30___.

Apply and Grow: Practice

Question 3.
50 – 30 = ?

Think 30 + _________ = 50
So, 50 – 30 = _________ .
50 – 30 = 20.

Explanation:

Think 30 + __20_______ = 50
So, 50 – 30 = ___20______ .

Question 4.
70 – 20 = ?

Think 20 + _________ = 70
So, 70 – 20 = _________ .
70 – 20 = 50.

Explanation:

Think 20 + ____50_____ = 70
So, 70 – 20 = __50_______ .

Question 5.
90 – 50 = ?

Think 50 + _________ = 90
So, 90 – 50 = _________ .
90 – 50 = 40.

Explanation:

Think 50 + _____40____ = 90
So, 90 – 50 = _____40____ .

Question 6.
MP Structure
Match the related addition and subtraction equations.
60 + 10 = 70Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  70 – 50 = 20
50 + 10 = 60Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  70 – 60 = 10
50 + 20 = 70Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  60 – 50 = 10

Explanation:
60 + 10 = 70 and 70 – 60 = 10 are related addition and subtraction equations because both deals with 60, 10 and 70.
50 + 10 = 60 and 60 – 50 = 10 are related addition and subtraction equations because both deals with 60, 10 and 50.
50 + 20 = 70 and 70 – 50 = 20 are related addition and subtraction equations because both deals with 70, 20 and 50.

Think and Grow: Modeling Real Life

A dentist has 40 toothbrushes. She gives away 20 of them. How many toothbrushes does she have left?

Model:

Subtraction equation:

______________ toothbrushes
Number of tooth brushes left = 20.

Explanation:
Total number of tooth brushes a dentist has = 40
Number of tooth brushes gave away = 20
Number of tooth brushes left = Total number of tooth brushes a dentist has – Number of tooth brushes gave away
= 40 – 20
= 20
Hence, Number of tooth brushes left = 20.

Show and Grow

Question 7.
An art room has 70 bottles of glitter. 30 have been used. How many bottles are left?

Model:

Subtraction equation:

______________ bottles
Number of bottles of glitter left = 40.

Explanation:
Total number bottles of glitter in an art room = 70
Number ofÂ  bottles of glitter used = 30
Number of bottles of glitter left = Total number bottles of glitter in an art room – Number ofÂ  bottles of glitter used
= 70 – 30
= 40.
Hence, Number of bottles of glitter left = 40.

### Use Addition to Subtract Tens Practice 8.7

Question 1.
70 – 40 = ?

Think 40 + __________ = 70
So, 70 – 40 = _________ .
70 – 40 = 30.

Explanation:

Think 40 + ____30______ = 70
So, 70 – 40 = ___30______ .

Question 2.
90 – 30 = ?

Think 60 + __________ = 90
So, 90 – 30 = _________ .
90 – 30 = 60.

Explanation:

Think 60 + _____30_____ = 90
So, 90 – 30 = ____60_____ .

Question 3.
MP Structure
Match the related addition and subtraction equations.
30 + 10 = 40Â  Â  Â  Â  Â  Â  Â  Â  Â  50 – 40 = 10
40 + 10 = 50Â  Â  Â  Â  Â  Â  Â  Â  Â  50 – 30 = 20
30 + 20 = 50Â  Â  Â  Â  Â  Â  Â  Â  Â  40 – 30 = 10

Explanation:
30 + 10 = 40 and 40 – 30 = 10 are related addition and subtraction equations because both deals with 40, 10 and 30.
40 + 10 = 50 and 50 – 40 = 10 are related addition and subtraction equations because both deals with 40, 10 and 50.
30 + 20 = 50 and 50 – 30 = 20 are related addition and subtraction equations because both deals with 30, 20 and 50.

Question 4.
Modeling Real Life
Newton has 80 newspapers to deliver. He delivers 50 of them. How many newspapers does he have left?

______________ newspapers
Number of newspapers left = 30.

Explanation:
Total number of newspapers to deliver = 80
Number of newspapers delivered = 50
Number of newspapers left = Total number of newspapers to deliver – Number of newspapers delivered
= 80 – 50
= 30.
Hence, Number of newspapers left = 30.

Review & Refresh

Question 5.
Make quick sketches to compare the numbers.

43 > 34.
34 < 43.

Explanation:
43 is greater than 34.

34 is lesser than 43.

### Lesson 8.8 Add Tens to a Number

Explore and Grow

15 + 10 = ________Â  Â  Â  Â  Â  Â  Â  Â 27 + 10 = __________
15 + 20 = ________Â  Â  Â  Â  Â  Â  Â  Â 27 + 20 = __________
15 + 30 = ________Â  Â  Â  Â  Â  Â  Â  Â 27 + 30 = __________
15 + 10 = ___25_____Â  Â  Â  Â  Â  Â  Â  Â 27 + 10 = ___37_______
15 + 20 = ___35_____Â  Â  Â  Â  Â  Â  Â  Â 27 + 20 = ____47______
15 + 30 = _____45___Â  Â  Â  Â  Â  Â  Â  Â 27 + 30 = ___57_______

Explanation:

Show and Grow

Question 1.
23 + 50 = ____________
23 + 50 =Â  73.

Question 2.
6 + 70 = ____________
6 + 70 = 76.

Apply and Grow: practice

Question 3.
27 + 40 = ____________
27 + 40 = 67.

Question 4.
8 + 80 = ____________
8 + 80 = 88.

Question 5.
60 + 35 = ____________
60 + 35 =Â  95.

Question 6.
30 + 44 = ____________
30 + 44 = 74.

Question 7.
____________ = 33 + 20
53 = 33 + 20.

Question 8.
____________ = 70 + 22
92= 70 + 22.

Question 9.
YOU BE THE TEACHER
Is Newton correct? Explain.

36 +50 = 86.
Newton is correct.

Explanation:
36 +50 = 86.
Hence, Newton is correct because the addition of both the addends is correct.

Think and Grow: Modeling Real Life

You count 8 birds on your way to school. You count 40 more on your way home. Your friend counts 45 birds in all. Who counts more birds?

Model:

Compare: ___________ â—‹ ____________

Who counts more birds?Â  Â  Â  Â  Â  Â  YouÂ  Â  Â  Â  Â  Â  Â Friend

I have counted 3 birds more than my friend.

Explanation:
Number of birds I counted on the way to school = 8
Number of birds I counted more on your way home = 40
Total number of birds my friend counts in all = 45
Total number of birds I counted in all = Number of birds I counted on the way to school – Number of birds I counted more on your way home
= 8 + 40
= 48.

Comparison:
Number of birds who counted more = Total number of birds I counted in all – Total number of birds my friend counts in all
= 48 – 45
= 3

Hence, I have counted 3 birds more than my friend.

Show and Grow

Question 10.
You make 21 snowballs. Your friend makes 11 small snowballs and 20 large snowballs. Who makes more snowballs?

Model:

Compare: ___________ â—‹ ____________

Who counts more birds?Â  Â  Â  Â  Â  YouÂ  Â  Â  Friend
Number of snow balls who made more = 10.

Explanation:
Total number of snow balls I made = 21
Total number of small snow balls my friend made =11
Total number of large snow balls my friend made = 20
Total number of snow balls my friend made = Total number of small snow balls my friend made + Total number of large snow balls my friend made
= 11 + 20
= 31

Comparison:
Number of snow balls who made more = Total number of snow balls my friend made – Total number of snow balls I made
=Â  31 – 21
= 10.

Hence, the Number of snow balls who made more = 10.

### Add Tens to a Number Practice 8.8

Question 1.
19 + 40 = __________
19 + 40 = 59.

Question 2.
60 + 23 = __________
60 + 23 = 83.

Question 3.
__________ = 5 + 90
95 = 5 + 90.

Question 4.
__________ = 37 + 30
67 = 37 + 30.

Question 5.
YOU BE THE TEACHER
Is Descartes correct? Explain.

Descartes is incorrect.

Explanation:
46 + 20 = 66.
Hence, Descartes is incorrect because he did not do the addition correctly.

Question 6.
Modeling Real Life
You have 24 glow sticks and buy 40 more. Your friend has 66 glow sticks. Who has more glow sticks?

Who has more glow sticks?Â  Â  Â  Â  Â  Â  Â  Â  Â YouÂ  Â  Â  Â  Â  Â  Â Friend

My friend has 2 glow sticks more than me.

Explanation:
Number of glow sticks I have = 24
Number of glow sticks I have purchased more = 40
Total number of glow sticks I have = Number of glow sticks I have + Number of glow sticks I have purchased more
= 24 + 40
= 64
Number of Â glow sticks my friend has = 66
Comparison:
Number of Â glow sticks who has more = Number of Â glow sticks my friend has – Total number of glow sticks I have
= 66 – 64
= 2

Hence, my friend has 2 glow sticks more than me.

Review & Refresh

Question 7.
Circle the solid shapes that stack.

Explanation:
In Geometry, Solids are three-dimensional shapes because they have three dimensions such as length, breadth and height. The bodies which occupy space are called solids.
here in the above picture, cone , cylinder ,cube are solid shapes that stack not sphere shape ball.

Question 1.
The tables show the numbers of seconds 3 pinwheels and 3 fops spin.

a. How many more seconds does the yellow top spin than the red pinwheel?
__________ seconds
Number of more seconds the yellow top spin than the red pinwheel taken = 50.

Explanation:
Number of seconds red pinwheel taken =Â  40
Number of seconds yellow pinwheel taken = 90
Number of more seconds the yellow top spin than the red pinwheel taken = Number of seconds red pinwheel taken – Number of seconds yellow pinwheel taken
= 90 – 40
= 50.
Hence, Number of more seconds the yellow top spin than the red pinwheel taken = 50.

b. The red pinwheel spins 30 fewer seconds than the red top. How long does the red top spin?

__________ seconds
The number of seconds the red top taken = 70.

Explanation:
Number of seconds the red pinwheels spins = 40
Let the number of seconds the red top taken be X
The number of seconds the red top taken – 30 =Â  Number of seconds the red pinwheels spins
(The red pinwheel spins 30 fewer seconds than the red top)
=>Â  X – 30 = 40
=> X = 40 + 30
=> X = 70
Hence, The number of seconds the red top taken = 70.

c. The blue pinwheel and the blue top spin for 96 seconds in all. How long does the blue pinwheel spin?

__________ seconds
Number of seconds blueÂ  pinwheel spin taken = 60.

Explanation:
Number of seconds blue top spin taken = 36
Total number of seconds the blue pinwheel and the blue top spins = 96
Number of seconds blue pinwheel spin taken = Number of seconds blue top spin taken – Total number of seconds the blue pinwheel and the blue top spins
= 96 – 36
= 60.
Hence, Number of seconds blue pinwheel spin taken = 60.

d. Which pinwheel spins the longest?
RedÂ  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â YellowÂ  Â  Â  Â  Â  Â  Â  Â  Â  Â Blue
The yellow pinwheel spins the longest than other pinwheels.

Explanation:
Number of seconds blue pinwheel spin taken = 60
Number of seconds yellow pinwheel spin taken = 90
Number of seconds red pinwheel spin taken = 40
Among, the three pinwheels, the yellow pinwheel spins the longest than other pinwheels.

### Mental Math: 10 More Homework & Practice 8.1

Use mental math.

Question 1.
58 + 10 = ___________
58 + 10 = 68.

Question 2.
15 + 10 = ___________
15 + 10 = 25.

Question 3.
29 + 10 = ___________
29 + 10 = 39.

Question 4.
41 + 10 = ___________
41 + 10 = 51.

Question 5.
10 + 7 = ___________
10 + 7 =Â  17.

Question 6.
10 + 36 = ___________
10 + 36 = 46.

Question 7.
84 + ___________ = 94
84 + 10= 94

Explanation:
Let the missing number be X.
84 + X = 94
X = 94 – 84
X = 10.

Question 8.
47 + ___________ = 57
47 + 10 = 57.
Explanation:
Let the missing number be X.
47 + X = 57
X = 57 – 47
X =10.

### Mental Math: 10 Less Homework & Practice 8.2

Use mental math.

Question 9.
24 – 10 = ___________
24 – 10 = 14.

Question 10.
78 – 10 = ___________
78 – 10 =Â  68.

Question 11.
31 – 10 = ___________
31 – 10 = 21.

Question 12.
95 – 10 = ___________
95 – 10 = 85.

Question 13.
___________ – 10 = 7
17 – 10 = 7.

Explanation:
Let the Missing minuend be X.
Subtrahend = 10
Difference = 7
Subtract the numbers:
X – 10 = 7
X = 7 + 10
X = 17.
Hence, 17 – 10 = 7.

Question 14.
___________ – 10 = 43
53 – 10 = 43.

Explanation:
Let the Missing minuend be X.
Subtrahend = 10
Difference = 43
Subtract the numbers:
X – 10 = 43
X = 43 + 10
X = 53.
Hence, 53 – 10 = 43.

### Add Tens Homework & Practice 8.3

Question 15.
60 + 20 = ?
__________ tens + ___________ tens = ___________ tens
So, 60 + 20 = ___________ .
60 + 20 = 80.

Explanation:
_______6___ tens + _______2____ tens = ______8_____ tens
So, 60 + 20 = _____80______ .

Question 16.
30 + 50 = ___________
30 + 50 = 80.

Question 17.
___________ + 30 = 90
60 + 30 = 90.

Explanation:
Let the missing addend be X.
sum = 90
X + 30= 90
X = 90Â  – 30
X = 60.
Hence, 60 + 30 = 90.

### Add Tens Using a Number Line Homework & Practice 8.4

Question 18.
50 + 40 = ___________

50 + 40 = 90.

Explanation:

Question 19.
MP Structure
Write an equation that matches the number line.

Equation:
20 + 30 =50.

Explanation:
20 + 10 +10 +10
= 30 +10 +10
= 40 + 10
= 50.

### Subtract Tens Homework & Practice 8.5

Question 20.
90 – 40 = ?
__________ tens – ___________ tens = ___________ tens
So, 90 – 40 = ___________ .
90 – 40 = 50.

Explanation:
___9__tens – __4_____ tens = ______5_____ tens
So, 90 – 40 = _50__________ .

Question 21.
70 – 40 = ___________
70 – 40 = 20.

Question 22.
80 – __________ = 60
80 – 20 = 60.

Explanation:
Let the missing number be X.
80 – X = 60
80 = 60 + X
80 – 60 = X
20 = X.

### Subtract Tens Using a Number Line Homework & Practice 8.6

Question 23.

60 – 40 = __________
60 – 40 = 20.

Explanation:

Question 24.
MP Structure
Write the equation that matches the number line.

Equation: 70 –Â  20 = 50.

Explanation:
Number line representation :
70 – 10 -10
= 60 -10
= 50.

### Use Addition to Subtract Tens Homework & Practice 8.7

Question 25.
80 – 60 = ?

Think 60 + __________ = 80
So, 80 – 60 = __________ .
80 – 60 = 20.

Explanation:

Think 60 + ____20______ = 80
So, 80 – 60 = _____20_____ .

Question 26.
Modeling Real Life
A mail carrier has 90 packages to deliver. She delivers 60 of them. How many packages are left?

______________ packages
Number of packages left = 30.

Explanation:
Number of packages are there for deliver = 90
number of packages she delivered = 60
Number of packages left = Number of packages are there for deliver – number of packages she delivered
= 90 – 60
= 30.
Hence, Number of packages left = 30.

### Add Tens to a Number Homework & Practice 8.8

Question 27.
27 + 50 = ____________
27 + 50 = 77.

Question 28.
_____________ = 80 + 12
92 = 80 + 12.

Conclusion: