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Then/Now You have already solved real-world problems using the percent equations. (Lesson 7–5) Find percent of increase and decrease. Solve real-world problems involving markup and discount.

Concept If the answer is positive, the percent of change is an increase. If the answer is negative, the percent of change is a decrease.

Example 1 Find the Percent of Change Find the percent of change from 20 students to 24 students. State whether the percent of change is an increase or decrease. Step 1Subtract to find the amount of change. 24 – 20 = 4final amount – original amount Step 2Write a ratio that compares the amount of change to the original amount. Express the ratio as a percent.

Example 1 Find the Percent of Change Cross multiply. Answer: 20%; increase Step 3The percent of change is positive, so it is a percent of increase = 20 x 20% = x Divide.

Example 1 A.–20%; decrease B.–25%; decrease C.20%; increase D.25%; increase What is the percent of change from 24 to 30 students?

Example 2 A.–17.9%; decrease B.–21.7%; decrease C.17.9%; increase D.21.7%; increase John had $420 in his checking account at the beginning of May. At the beginning of June he had $345. What was the percent of increase or decrease to the nearest tenth?