Warm Up Solve. 1. x – 17 = 32 2. y + 11 = 41 3. = 18 4. 12x = 108 3. = 18 4. 12x = 108 5. x – 9 = 20 w 5

Students in a physical education class were running 40-yard dashes as part of a fitness test. The slowest time in the class was 3.84 seconds slower than the fastest time of 7.2 seconds. You can write an equation to represent this situation. The slowest time s minus 3.84 is equal to the fastest time of 7.2 seconds. s – 3.84 = 7.2

Remember! You can solve an equation by performing the same operation on both sides of the equation to isolate the variable.

Additional Example 1: Solving Equations by Adding or Subtracting Solve. A. n – 2.75 = 8.3 B. a + 32.66 = 42

Check It Out: Example 1 Solve. A. a – 1.35 = –22 B. b + 27.51 = 36

Additional Example 2A: Solving Equations by Multiplying or Dividing Solve. x = 5.4 4.8

Additional Example 2B: Solving Equations by Multiplying and Dividing Solve. 9 = 3.6d

Check It Out: Example 2A Solve. Justify your steps. c 9.6 = 8

Check It Out: Example 2B Solve. Justify your steps. 9 = 2.5 d

Understand the Problem Additional Example 3: Problem Solving Application The fee to place a standard classified add is $29.95 for 25 words. The cost for each additional word is $0.25. Isabel has $33.20 to place a classified ad. How many additional words can she purchase? 1 Understand the Problem List the important information: • The fee to place a classified add is $29.95 for 25 words. • The cost for each additional word is $0.25. • Isabel has $33.20 to place an ad.

Additional Example 3 Continued 2 Make a Plan Because you know how much money Isabel has to spend, you can write an equation with w being the number of additional words she can purchase. 29.95 + 0.25w = 33.20

Additional Example 3 Continued Solve 3 29.95 + 0.25w = 33.20

Additional Example 3 Continued 4 Look Back You can round 33.20 to 33, and 29.95 to 30 to estimate how many additional words Isabel can include.

Check It Out: Example 3 Hannah is driving 525 miles to visit her family. She drove 138.1 miles before she stop to get gas. If she averages 53 miles per hour for the rest of her trip, how many more hours will it take to arrive at her destination? 138.1 + 53h = 525