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:

Image showing 25 over 125 multiplied by 100 percent equals 1 fift multiplied by 100 percent equals 0.2 multiplied by 100 percent equals 20 percent. Arrow are pointing at 25 over 125 saying actual decrease, arrow point at 100 percent saying original cost (or amount) and arrow point at 20 percent saying percent decrease

In other words, the price of the sneakers dropped by 20%. The process for calculating percent increases and decreases can be summarized as follows: percentage increase or decrease equation left hand side equals right hand side actual increase or decrease divided by original amount multiplication 100.

8.3.1 Percent Increase/Decrease

8.3.3 Ups and Downs