-83.5% is the change from 515 to 85
Calculation steps:
[( 85 - 515 ) ÷ 515] x 100 = -83.5%
Formula
Percentage change = [(85 - 515) / 515] x 100
Subtract the new number by the original number
85 - 515 = -430
-430 ÷ 515 = -0.8349514563106796
-0.8349514563106796 x 100 = -83.5%