500% is the change from 15 to 90
Calculation steps:
[( 90 - 15 ) ÷ 15] x 100 = 500%
Formula
Percentage change = [(90 - 15) / 15] x 100
Subtract the new number by the original number
90 - 15 = 75
75 ÷ 15 = 5
5 x 100 = 500%
Example