8.3.2 Percent Decrease
Whether it’s coupons you receive in the mail or a raise in your salary, you know that percentages are used to describe increases or decreases.
For example, suppose last week a pair of sneakers cost $125, and this week the same pair costs $100. The price decreased by $25, which is referred to as the actual decrease.
To express the discount as a percentage, first write the actual decrease as a fraction of the original cost, then change the fraction into a percentage.
So the percent decrease is:
In other words, the price of the sneakers dropped by 20%. The process for calculating percent increases and decreases can be summarized as follows: .