1. Solve the equation.
1. x = 25 5 6
ANSWER 30
2. (6x + 3) = 14 2 3
ANSWER 3

2. Solve the equation.
– 7 = 12 g 5
ANSWER 95
4. You buy three identical polyester film balloons and a
birthday card. The card costs $3.95. Find the cost of each balloon if your total bill before tax was $33.80.
ANSWER
$9.95

3. EXAMPLE 1
Write a ratio
VOLLEYBALL
A volleyball team plays 14 home matches and 10 away
matches.
a. Find the ratio of home matches to away matches.
b. Find the ratio of home matches to all matches.
SOLUTION = 7 5 a.
home matches
away matches 14 10 b.
home matches
all matches 14 = 24 7 12

4. EXAMPLE 1
GUIDED PRACTICE
for Example 1
Derek and his brother decide to combine their CD collections. Derek has 44 CDs, and his brother has 52 CDs. Find the specified ratio.
1. The number of Derek’s CDs to the number of his brother’s CDs. 11 13
ANSWER
2. The number of Derek’s CDs to the number of CDs in the entire collection. 11 24
ANSWER

5. EXAMPLE 2 Solve a proportion x 30 Solve the proportion 11 6 = . 11 6 x
Write original proportion. 11 6 x 30 =
Multiply each side by 30.
330 6 = x
Simplify.
55 = x
Divide.

6. EXAMPLE 2
GUIDED PRACTICE
for Example 2
Solve the proportion. Check your solution. 4 7 w 35 = 3. 20
ANSWER

7. EXAMPLE 2
GUIDED PRACTICE
for Example 2
Solve the proportion. Check your solution. m 12 9 2 = 4. 54
ANSWER

8. EXAMPLE 2
GUIDED PRACTICE
for Example 2
Solve the proportion. Check your solution. 5 9 z 54 = 5. 30
ANSWER

9. EXAMPLE 3
Solve a multi-step problem
ELEVATORS
The elevator that takes passengers from the lobby of the John Hancock Center in Chicago to the observation level travels 150 feet in 5 seconds. The observation level is located on the 94th floor, at 1029 feet above the ground. Find the time it takes the elevator to travel from the lobby to the observation level.

10. Solve a multi-step problem
EXAMPLE 3
Solve a multi-step problem
SOLUTION
STEP 1
Write a proportion involving two ratios that compare the amount of time the elevator has ascended with the distance traveled. x
1029 = 5
Seconds
150
feet
STEP 2
Solve the proportion.

11. Solve a multi-step problem
EXAMPLE 3
Solve a multi-step problem 5
150 x
1029 =
Write proportion. 5
150 =
1029 x
Multiply each side by 1029.
5145
150 = x
Simplify.
34.3 = x
Use a calculator.
ANSWER
The elevator travels from the lobby to the observation level in 34.3 seconds.

12. Daily Homework Quiz
Solve the proportion. 32 28 3. = m 14 16
ANSWER 4.
A printer can print 12 color pages in 3 minutes. How many color pages can the printer print in 9 minutes? Write and solve a proportion to find the answer.
ANSWER 12 3 = x 9
; 36 color pages

13. 2.7 Solving Proportions
Using Cross Products

14. Use the cross products property
EXAMPLE 1
Use the cross products property
Solve the proportion = 8 x 6 15 = 8 x 6 15
Write original proportion.
8 15 = x 6
Cross products property
120 = 6x
Simplify.
20 = x
Divide each side by 6.
The solution is 20. Check by substituting 20 for x in the original proportion.
ANSWER

15. Write and solve a proportion
EXAMPLE 3
Write and solve a proportion
Each day, the seals at an aquarium are each fed 8 pounds of food for every 100 pounds of their body weight. A seal at the aquarium weighs 280 pounds.
How much food should the seal be fed per day?
Seals
SOLUTION
STEP 1
Write a proportion involving two ratios that compare the amount of food with the weight of the seal. x
280 = 8
amount of food
100
weight of seal

16. Write and solve a proportion
EXAMPLE 3
Write and solve a proportion
STEP 2
Solve the proportion. 8
100 x
280 =
Write proportion.
= 100 x
Cross products property
2240 = 100x
Simplify.
22.4 = x
Divide each side by 100.
ANSWER
A 280 pound seal should be fed 22.4 pounds of food per
day.

17. EXAMPLE 1
GUIDED PRACTICE
for Examples 1, 2, and 3
Solve the proportion. Check your solution. = 4 a 24 30 1. 5
ANSWER

18. EXAMPLE 2
GUIDED PRACTICE
for Examples 1, 2, and 3
Solve the proportion. Check your solution. 3 x = 2
– 6 2. 18
ANSWER

19. EXAMPLE 2
GUIDED PRACTICE
for Examples 1, 2, and 3
Solve the proportion. Check your solution. 4 m 5 =
m – 6 3. 18
ANSWER

20. Daily Homework Quiz 10 35 = y 42 1.
ANSWER 12 13 h = 26 16 2.
ANSWER 8 5r 6 = 15 2 3.
ANSWER 9