Write an Equation
Name
Chapter 4, Lesson 7A
Objective: To solve problems by writing and solving equations
To solve some problems, you can write an equation. To solve equations, you can
use properties of operations.
Use the Subtraction Property of Equality
One day, Tim rode 32 miles on his bike. He
rode 8 miles before noon. How many miles
did he ride after noon?
Let d represent the number of miles
Tim rode after noon.
Write the equation.
total
miles
miles
miles ! before # after
noon
noon
Solve.
32 $ 8 ! 8 # d $ 8
Copyright © by William H. Sadlier, Inc. All rights reserved.
One day, Tim rode 32 miles on his bike. His
average speed was 8 miles per hour. How
many hours did he ride?
Let t represent the number of hours
Tim biked.
Write the equation.
distance ! speed " time
Solve.
32 ! 8 " t
32 % 8 ! 8 " t % 8
32 ! 8 # d
24 ! d
Use the Division Property of Equality
4!t
Subtract 8 from
both sides.
So, Tim rode 24 miles after noon.
Divide both
sides by 8.
So, Tim rode for 4 hours.
Practice
Solve by writing an equation.
1. Becky and Andrew both collect baseball
cards. Andrew has 250 cards. He has
12 more cards than Becky. How many
baseball cards does Becky have?
Andrew’s ! Becky’s # 12
! b
! b
#
2. Dana’s bookcase has 6 shelves. Each shelf
has the same number of books. There are
a total of 126 books in the bookcase. How
many books are on each shelf?
total ! shelves " books per shelf
!
"b
! b
Discuss and Write
3. Look back at the problems about Tim. Which words in each
problem helped you decide the equation to write? Why?
Grade 6, Lesson 4-7A
5106-6_WB06_219 219
219
2/12/13 1:11 PM
Write an Equation
Name
Chapter 4, Lesson 7A
Practice
Solve by writing an equation.
4. Michael is bagging walnuts for a food
sale. He puts 64 walnuts in a bag. How
many walnuts will he put in 6 bags?
5. There are 395 students in sixth grade
at Ali’s school. That is 33 more students
than are in seventh grade. How many
seventh graders are there at Ali’s school?
total walnuts ! bags " number in a bag
!
sixth graders ! seventh graders #
"
!
!
#
!
Problem Solving
8. Martha uses 4 cups of flour to make a
loaf of bread. She used 128 cups of flour
in April. How many loaves of bread did
she make?
9. The 25 students in Ms. Johnson’s class each
read an average of 60 hours each month.
The 30 students in Mr. Ryan’s class each
read an average of 50 hours each month.
Which class reads more? How much more?
What’s the Error?
10. Lucy needs to know how many yards of tape are in a 45-ft roll of tape.
She knows that 3 ft ! 1 yard, so she lets y represent the number of yards.
She writes and solves this equation.
y ! 3 " 45
Copyright © by William H. Sadlier, Inc. All rights reserved.
Solve. Use a strategy that works best for you. Show your work.
6. Billy’s school is running a canned food
7. Roger bought 40 special forever stamps.
drive. They collected 480 cans in the
They cost more than $20. He gave
morning. They collected 70 more cans in
8 stamps to his sister and 9 to his brother.
the afternoon than in the morning. How
How many forever stamps does he have
many cans did Billy’s school collect in all?
now?
y ! 135 yards
Find and correct Lucy’s error.
220
Grade 6, Lesson 4-7A
5106-6_WB06_220 220
For additional Practice, go to page 274 in this Workbook.
Then go to Lesson 4-8, pages 136–137 in the Student Book.
2/12/13 1:11 PM