To find the percent change (increase or decrease), use the formula given in Example .
Example 1
Last year, Harold earned $250 a month at his after‐school job. This year, his after‐school earnings have increased to $300 per month. What is the percent increase in his monthly after‐school earnings?
First, circle what you're looking for— percent increase. Percent change (percent increase, percentage rise, % difference, percent decrease, and so forth) is always found by using the equation
Therefore,
The percent increase in Harold's after‐school salary is 20%.