1. Percent of Change
7.RP.3 Use proportional relationships to SOLVE multi-step ratio and percent problems. Examples: simple interest, tax, markups and markdowns, gratuities and commissions, fees, percent increase and decrease, percent error. 1

2. What is Percent of Change?
Common Examples of Percent of Increase
Common Examples of Percent of Decrease
Sales tax on an item purchased
Items that are on sale at a store
Finding a total bill at a restaurant including tip
Population decreases

3. Percent of Change
Percent of Change: the amount, stated as a percent, that a number increases or decreases.
Percent of Increase: The amount, stated as a percent, that a number goes up.
Percent of Decrease: The amount, stated as a percent, that a number goes down.

4. Percent of Change
Percent of Change = amount of change
original amount

5. Finding Percent of Change
27 is decreased to 20
27 – 20 = 7
Percent of Change = amount of change
original amount
Percent of Change = 7 27
Percent of Change ≈
Percent of Change ≈ 25.9%

6. Finding Percent of Change
32 is increased to 67
67 – 32 = 35
Percent of Change = amount of change
original amount
Percent of Change = 35 32
Percent of Change ≈
Percent of Change ≈ 109.4%

7. Finding Percent of Change
20 is decreased to 11
20 – 11 = 9
Percent of Change = amount of change
original amount
Percent of Change = 9 20
Percent of Change ≈ 0.45
Percent of Change ≈ 45%

8. Finding Percent of Change
42 is increased to 72
72 – 42 = 30
Percent of Change = amount of change
original amount
Percent of Change = 30 42
Percent of Change ≈
Percent of Change ≈ 71.4%

9. Finding Percent of Change Your Turn…
24 is increased to 30
Percent of Change = amount of change
original amount

10. Finding Percent of Change Your Turn…
56 is decreased to 14
Percent of Change = amount of change
original amount

11. Finding Percent of Change Your Turn…
105 is decreased to 32
Percent of Change = amount of change
original amount

12. Finding Percent of Change Word Problems
Zack Cole shot an 86 on the golf course on Monday. On Friday he shot a 95. What is the % of change?
86 increased to 95
Percent of Change = amount of change = 9
original amount
Percent of Change = 10.5%

13. Finding Percent of Change Word Problems
Kelly Dyer became a great writer. She had a picnic each year to celebrate the date of her first published work. The 1st year 50 people came. The 2nd year 30 people came. What is the percent of change?
50 decreased to 30
Percent of Change = amount of change = 20
original amount
Percent of Change = 40%

14. Finding Percent of Change Word Problems: Your Turn
Jack bought a stereo on sale for $231. The original price was $385. What was the percent of decrease in price?

15. Finding Percent of Change Word Problems: Your Turn
Angela Smyre became a famous architect. She made $90,000 in In 2005 she made $120,000. What is the percent of increase?

16. Finding Percent of Change Word Problems: Your Turn
Amber Robinson became a foster mother, because she is so good with children. She took care of 8 children in In 2004 she had only 5. What is the percent of decrease?