Page 204 - Math Course 1 (Book 1)

Percent of Increase and Decrease

Mo. 6

Lesson 7
Let’s Begin

KEY CONCEPTS:
1. Find percent of decrease. Find Percent of Change
2. Find percent of increase

Example

MO. 6 - L7a Find the percent of change from 325 to 390.

Finding the Percent of Step 1
Decrease Subtract to f nd the amount of change.
390 – 325 = 65 new amount – original amount

Vocabulary A-Z Step 2
Let us learn some vocabulary Write a ratio that compares the amount of change
to the original amount. Express the ratio as a
percent.

amount of change
Percent of Change =
Percent of Change original amount

tells the percent an amount has increased or = 65 Substitution.
decreased in relation to the original amount. 325

Write the decimal as
= 0.20 or 20%
amount of change
Percent of Change = a percent.
original amount
The percent of change from
Answer
325 to 390 is 20%.
Percent of Decrease
Find Percent of Decrease
When the amount decreases, the percent of change
is negative. You can state a negative percent of
change as a percent of decrease. Example

amount of change
Percent of Change = CLOTHING
opening points A $110 sweater is on sale for $88. What is the
percent of change?
–508.32
Substitution =
2246.74 Step 1
Subtract to f nd the amount of change.
Write the decimal as = –0.266 or –22.6% 88 – 110 = –22 sale price – original price.
a percent
Step 2
Compare the amount of change to the original
The percent of price.
change is –22.6%.
Percent of Change = amount of change
It is a percent of original price
decrease.
–22
= Substitution.
110

196