1. Warm Up
Problem of the Day
Lesson Presentation
Lesson Quizzes

2. Warm Up
Divide. 72 12 65 5 6 13 40 10 60 6 10 4
130 5 91 7 26 13

3. Problem of the Day
Katie’s little brother is building a tower with blocks. He adds 6 blocks and then removes 4 blocks. If he adds 8 more blocks, the tower will have twice as many blocks as when he started. How many blocks did he start with?
5 blocks

4. Learn to solve whole-number multiplication equations.

5. Multiplication and division are inverse operations
Multiplication and division are inverse operations. To solve an equation that contains multiplication, use division to “undo” the multiplication.
4m = 32
Caution !
4m = 32
4m means “4  m.” 4 4
m = 8

6. Additional Example 1A: Solving Multiplication Equations
Solve the equation. Check your answer.
5p = 75
p is multiplied by 5.
5p = 75
Divide both sides by 5 to undo the multiplication. 5 5
p = 15
Check 5p = 75
5(15)= 75 ?
Substitute 15 for p in the equation.
75 = 75 ? 
15 is the solution.

7. Additional Example 1B: Solving Multiplication Equations
Solve the equation. Check your answer.
16 = 8r
r is multiplied by 8.
16 = 8r
Divide both sides by 8 to undo the multiplication. 8 8
2 = r
Check 16 = 8r
16 = 8(2) ?
Substitute 2 for r in the equation.
16 = 16 ? 
2 is the solution.

8. Solve the equation. Check your answer.
Check It Out: Example 1A
Solve the equation. Check your answer.
8a = 72
a is multiplied by 8.
8a = 72
Divide both sides by 8 to undo the multiplication. 8 8
a = 9
Check 8a = 72
8(9)= 72 ?
Substitute 9 for a in the equation.
72 = 72 ? 
9 is the solution.

9. Solve the equation. Check your answer.
Check It Out: Example 1B
Solve the equation. Check your answer.
18 = 3w
w is multiplied by 3.
18 = 3w
Divide both sides by 3 to undo the multiplication. 3 3
6 = w
Check 18 = 3w
18 = 3(6) ?
Substitute 6 for w in the equation.
18 = 18 ? 
6 is the solution.

10. Additional Example 2: Problem Solving Application
The area of a rectangle is 56 square inches. Its length is 8 inches. What is its width?

11. Understand the Problem
Additional Example 2 Continued 1
Understand the Problem
The answer will be the width of the rectangle in inches.
List the important information:
The area of the rectangle is 56 square inches.
The length of the rectangle is 8 inches.
Draw a diagram to represent this information. w 56 8

12. Additional Example 2 Continued
Make a Plan
You can write and solve an equation using the formula for area. To find the area of a rectangle, multiply its length by its width.
A = lw w
56 = 8w l

13. Additional Example 2 Continued
Solve 3
56 = 8w
w is multiplied by 8.
56 = 8w
Divide both sides by 8 to undo the multiplication. 8 8
7 = w
So the width of the rectangle is 7 inches.

14. Additional Example 2 Continued4
Look Back
Arrange 56 identical squares in a rectangle. The length is 8, so line up the squares in rows of 8. You can make 7 rows of 8, so the width of the rectangle is 7.

15. Check It Out: Example 2
The area of a rectangle is 48 square inches. Its width is 8 inches. What is its length?

16. Understand the Problem
Check It Out: Example 2 1
Understand the Problem
The answer will be the length of the rectangle in inches.
List the important information:
The area of the rectangle is 48 square inches.
The width of the rectangle is 8 inches.
Draw a diagram to represent this information. 48 8 l

17. Check It Out: Example 2 Continued
Make a Plan
You can write and solve an equation using the formula for area. To find the area of a rectangle, multiply its length by its width.
A = lw w
48 = l8 l

18. Check It Out: Example 2 Continued
Solve 3
48 = 8l
l is multiplied by 8.
48 = 8l
Divide both sides by 8 to undo the multiplication. 8 8
6 = l
So the length of the rectangle is 6 inches.

19. Check It Out: Example 2 Continued4
Look Back
Arrange 48 identical squares in a rectangle. The width is 8, so line up the squares in columns of 8. You can make 6 columns of 8, so the length of the rectangle is 6.

20. Lesson Quizzes
Standard Lesson Quiz
Lesson Quiz for Student Response Systems

21. Lesson Quiz
Solve each equation.
1. 10y = 300
2. 2y = 82
3. 63 = 9y
4. 78 = 13x
y = 30
y = 41
y = 7
x = 6
5. The area of a board game is 468 square inches. Its width is 18 inches. What is the length?
26 inches

22. Lesson Quiz for Student Response Systems
1. Solve the equation 2x = 88.
A. x = 90
B. x = 86
C. x = 48
D. x = 44

23. Lesson Quiz for Student Response Systems
2. Solve the equation 3y = 75.
A. y = 25
B. y = 35
C. y = 75
D. y = 78

24. Lesson Quiz for Student Response Systems
3. Solve the equation 72 = 8x.
A. x = 80
B. x = 64
C. x = 9
D. x = 8

25. Lesson Quiz for Student Response Systems
4. Solve the equation 91 = 7y.
A. y = 13
B. y = 17
C. y = 73
D. y = 84

26. Lesson Quiz for Student Response Systems
5. The area of Carl’s rectangular flower garden is 192 square feet. Its length is 16 feet. What is the width?
A. 8 feet
B. 12 feet
C. 14 feet
D. 16 feet