-83% is the change from 500 to 85
Calculation steps:
[( 85 - 500 ) ÷ 500] x 100 = -83%
Formula
Percentage change = [(85 - 500) / 500] x 100
Subtract the new number by the original number
85 - 500 = -415
-415 ÷ 500 = -0.83
-0.83 x 100 = -83%
Example