All the solutions provided in McGraw Hill My Math Grade 3 Answer Key PDF Chapter 9 Lesson 5 Write Expressions will give you a clear idea of the concepts.
McGraw-Hill My Math Grade 3 Answer Key Chapter 9 Lesson 5 Write Expressions
The four operations are addition, subtraction, multiplication, and division. An expression is a number or a combination of numbers and operations. An expression does not have an equals sign.
Math in My World
Example 1
Alice invited three friends to play in her backyard. Write an expression to represent the total number of friends.
Use numbers. 1 + ______________
Use words. _____________ plus three, or __________ more than one
Answer:
1 + 3 = 4
Explanation:
Given, Alice invited three friends to play in her backyard.
Then, one plus three or three more than one
That means, 1 + 3 = 4
So, The total number of friends are 4
Example 2
Five nails were hammered in the wood. One nail bent. Write an expression to represent the number of good nails left.
Use numbers. 5 – ______________
Use words. five minus ___________, or _____________ less than five
Answer: The number of good nails left are four.
Explanation:
Given, Five nails were hammered in the wood. One nail bent.
Then five minus one or one less than five.
that means, 5 – 1 = 4
So, The number of good nails left are four
Example 3
Tracy bought 3 magnets. Scott has two times as many. Then Scott buys one more. Write an expression to represent the total number of magnets Scott has.
Use pictures.
Helpful Hint
Parentheses tell you what to do first.
Use numbers. (___________ × 2) + 1
Use words. two _____________ three plus ____________, or, _____________ groups of three plus one more
Answer: Scott has 7 magnets in total.
Explanation:
Given, Tracy bought 3 magnets. Scott has two times as many. Then Scott buys one more.
That means , ( 3 × 2 ) + 1
Multiply the factors inside the parentheses first.
6 + 1 = 7
So, Scott has 7 magnets in total.
Talk Math
How did you know what operations to use in Example 3?
Answer: Parentheses tell you what to do first.
Explanation:
For example,
( 6 × 2 ) × 3
Multiply the factors inside the parentheses first.
12 × 3 = 36
So, 6 × ( 2 × 3 ) = 36.
So, Parentheses tell you what to do first.
Guided Practice
Model each expression with pictures, numbers, and words.
Question 1.
Jeff had 8 crayons. He lost 5 of them.
Answer: Jeff has 3 crayons left.
Explanation:
Given, Jeff had 8 crayons. He lost 5 of them
In Numbers , 8 – 5 = 3
In words , five less than eight is three
In picture, 
So, Jeff has 3 crayons left.
Question 2.
A carpenter has six nails. She went to the store to buy three more. She used 2 nails.
Answer: 6 + 3 – 2 = 7
Explanation:
Given, A carpenter has six nails.
She went to the store to buy three more. She used 2 nails.
In numbers, 6 + 3 – 2 = 7
In words, six plus three minus two equals seven.
Independent Practice
Use numbers and operations to write each phrase as an expression.
Question 3.
4 more than 7
Answer: 4 + 7 = 11
Explanation:
Given, 4 more than 7
In numbers, 4 + 7 = 11
In words, four plus seven equals eleven.
Question 4.
the total of 5 rows of 6 chairs
Answer: 5 × 6 = 30
Explanation:
Given, the total of 5 rows of 6 chairs
In numbers, 5 × 6 = 30
In words, five multiplied by six equals thirty
Question 5.
half of 18
Answer: 18 ÷ 2 = 9
Explanation:
Given, half of 18
In numbers, 18 ÷ 2 = 9
In words, eighteen divided by two equals nine
Question 6.
3 people equally divide $21
Answer: each gets $7
Explanation:
Given, 3 people equally divide $21
In numbers, 21 ÷3 = 7
In words, twenty one divided by 3 equals seven
So, each gets $7.
Question 7.
difference between 89 and 80
Answer: 89 – 80 = 9
Explanation:
Given, difference between 89 and 80
In numbers, 89 – 80 = 9
In words, eighty nine minus eighty equals nine
Question 8.
6 groups with 6 people in each
Answer: 6 × 6 = 36
Explanation:
Given, 6 groups with 6 people in each
In numbers, 6 × 6 = 36
In words , six multiplied by six equals thirty six
So, There are 36 people in total.
There are 6 nails in the toolbox. Write an expression to tell how many there will be when there are:
Question 9.
2 fewer nails
Answer: There will be 4 nails left in the toolbox
Explanation:
Given, There are 6 nails in the toolbox.
and 2 fewer nails
That means , 6 – 2 = 4
So, There will be 4 nails left in the toolbox
Question 10.
4 times as many nails
Answer: There will be 24 nails left in the toolbox
Explanation:
Given, There are 6 nails in the toolbox.
and 4 times as many nails
That means , 6 × 4 = 24
So, There will be 24 nails left in the toolbox
Question 11.
half as many nails
Answer: There will be 3 nails left in the toolbox
Explanation:
Given, There are 6 nails in the toolbox.
and half as many nails
That means , 6 ÷ 2= 3
So, There will be 3 nails left in the toolbox
Question 12.
10 more nails
Answer: There will be 16 nails left in the toolbox
Explanation:
Given, There are 6 nails in the toolbox.
and 10 more nails
That means , 6 + 10 = 16
So, There will be 16 nails left in the toolbox
Question 13.
3 equal groups of nails
Answer: There will be 18 nails left in the toolbox
Explanation:
Given, There are 6 nails in the toolbox.
and 3 equal groups of nails
That means , 6 × 3 = 18
So, There will be 18 nails left in the toolbox
Write an expression for each.
Question 14.
the cost of 5 bottles of glue
Answer: The total cost is $50
Explanation:
Given, cost of each glue bottle is $10
Then, for 5 bottles it will be,
5 × 10 = 50
So, The total cost is $50
Question 15.
the number of nails for 90c
Answer: the number of nails for 90c are 900
Explanation:
Given, the number of nails for 90c
Then for 90c it will be,
90 × 10 = 900
So, the number of nails for 90c are 900
Question 16.
the total cost of a spool of wire, tape measure, and a bottle of glue
Answer: the total cost of a spool of wire, tape measure, and a bottle of glue is $194
Explanation:
Given, cost of spool of wire is $89
cost of glue bottle is $10
cost of tape measure is $95
Then it will be, 89 + 95 + 10 = 194
So, the total cost of a spool of wire, tape measure, and a bottle of glue is $194.
Problem Solving
Mathematical PRACTICE Model Math Write an expression for each situation.
Question 17.
There were 6 groups of scouts. Each group earned 9 Build-It badges.
Answer: 6 × 9 = 54
Explanation;
Given, There were 6 groups of scouts. Each group earned 9 Build-It badges.
Then it will be, 6 × 9 = 54
So hey built badges in all are 54.
Question 18.
Mr. Lewis bought a flat of flowers for $22. How much change should he receive if he paid with two $20 bills?
($20 + $20) _____________
Answer: The change he received is $18.
Explanation:
Given, Mr. Lewis bought a flat of flowers for $22.
if he paid with two $20 bills
Then it will be, 20+20 = 40
40 – 22 = 18
So, The change he received is $18.
Question 19.
Each package of tape is 9 feet long. When Taryn buys 2 rolls, how many yards of tape will she have? (Hint: 1 yard = 3 feet)
(2 × 9) ______________
Answer: She needs 6 yards of tape
Explanation:
Given, Each package of tape is 9 feet long. When Taryn buys 2 rolls,
1 yard = 3 feet
Then 2 × 9 = 18 feet
6 × 3 = 18 feet
So, She needs 6 yards of tape
HOT Problems
Question 20.
Mathematical PRACTICE Which One Doesn’t Belong? Circle the phrase that does not belong. Explain.
Answer: The last phrase does not belong to the group.
Explanation:
Question 21.
Building on the Essential Question What kinds of specific words or phrases can be used to represent each of the four operations?
Answer: The basic four operation are addition , subtraction, division and multiplication
Explanation:
For example, addition will be , 5 + 3 = 8
subtraction will be , 4 – 2 = 2
division will be, 36 ÷ 6 = 6
multiplication will be, 7 × 9 = 63
McGraw Hill My Math Grade 3 Chapter 9 Lesson 5 My Homework Answer Key
Practice
Question 1.
Annette has 6 pencils. She divides them evenly among 3 friends. Model the expression with a picture, numbers, and words.
Answer: each friend gets 2 pencils.
Explanation:
Given, Annette has 6 pencils. She divides them evenly among 3 friends.
In numbers, 6 ÷ 3 = 2
In words, six divided by three equals two
Use numbers and operations to write each phrase as an expression.
Question 2.
4 boxes with 2 shoes in each
Answer: 4 × 2 = 8
Explanation:
Given, 4 boxes with 2 shoes in each
each box has 2 shoes
Then it will be, 4 × 2 = 8
Question 3.
the difference between 58 and 47
Answer: 58 – 47 = 11
Explanation:
Given, the difference between 58 and 47
Then numerically it will be,
58 – 47 = 11.
Question 4.
5 more than 12
Answer: 5 + 12 = 17
Explanation:
Given, 5 more than 12
Then numerically it will be,
5 + 12 = 17 .
Question 5.
30 books shared equally by 10 people
Answer: each one gets 3 books
Explanation:
Given, 30 books shared equally by 10 people
Then numerically it will be,
30 ÷ 10 = 3
So, each one gets 3 books.
Problem Solving
Mathematical PRACTICE Model Math Write an expression for each situation.
Question 6.
Stella read all but one of the 5 books she took on vacation.
Answer: she read 4 books
Explanation:
Given, Stella read all but one of the 5 books she took on vacation.
Then numerically it will be,
5 – 1 = 4
So, she read 4 books
Question 7.
Ms. Benson had a box of 8 popsicles. She bought another box of 4 popsicles. Ms. Benson divided the popsicles among her 2 children.
(____________) ÷ 2
Answer: 12 ÷ 2 = 6
Explanation:
Given, Ms. Benson had a box of 8 popsicles. She bought another box of 4 popsicles.
Ms. Benson divided the popsicles among her 2 children.
Then numerically , ( 8 + 4 ) ÷ 2
12 ÷ 2 = 6
Question 8.
Frieda bought 3 packs of 8 candles. Then she found 1 candle at home.
(3 × 8) ______________
Answer: (3 × 8) + 1
Explanation:
Given, Frieda bought 3 packs of 8 candles.
Then numerically it will be, (3 × 8)
Then she found 1 candle at home.
(3 × 8) + 1.
Vocabulary Check
Match each vocabulary word with its example.
Answer: 
Explanation:
Expressions in math are mathematical statements that have a minimum of two terms containing numbers or variables, or both, connected by an operator in between.
Operations is a mathematical action. Addition, subtraction, multiplication, division.
Test Practice
Question 11.
Zoe had 9 bracelets. She lost 1 and gave 3 to Blaire. Which expression matches the situation?
(A) 9 – 3
(B) (9 – 1) + (9 – 3)
(C) 9 – 1 – 3
(D) (9 – 1) + 3
Answer: C
Explanation:
Given, Zoe had 9 bracelets. She lost 1 and gave 3 to Blaire.
Then numerically it will be,
( 9 – 1 ) – 3 = 5
So, Zoe has 5 bracelets.