To calculate for the percent of decrease:
First: work out the difference between the two numbers that you are given with.
Decrease = Original Number - New Number
Second: divide the decrease by the original number and multiply the answer by 100.
In formula terms it would look like this percent of decrease = Decrease ÷ Original
Number × 100
= (87-75) / 87 x 100
= 12/87 x 100
= 0.137931034 x 100
=13.79%
