Percent Change: Percent Increase / Percent

Decrease

Objective:

Learn to solve problems involving percent increase and percent decrease.

Gaby went to Kalas and wanted to buy a really cool red dress. The dress was on sale 25% off. If the original price of the dress was $165 dollars, how much will the price be reduced?

When a price or number changes, you can use a formula to describe the increase or decrease.

The Formula is…

Percent change = amount of change 100 original amount

So you have to substitute the values…. 25 = X 100 $165

100 X = 4125 100 100

X = 41.25

Example 2: Find the percent increase or decrease, if 15 is increased to 20.

Percent change = amount of change 100 original amount P = 5 100 15

15 P = 500 15 15

P = 33.3%

Example 3:

Find the amount of increase or decrease if 75 is increased by 40%.

Percent change = amount of change 100 original amount

40 = X 100 75 100 X = 3000 X = 30

Your Example: Find the percent of increase or decrease if 96 is decreased to 72.

Percent change = amount of change 100 original amount

Homework:Find each percent increase or decrease. 1. 125 is decreased to 2.

2. 360 is increased to 361.

3. 84 is decreased to 28.

4. 615 is decreased to 450.

5. 460 is increased to 500.

Find the amount of increase or decrease. 6. 58 is increased by 72%.

7. 28 is increased by 150%.

8. 506 is decreased by 57%.

9. 4 is increased by 12%.

10. 48 is increased by 35%.