-89.57% is the change from 815 to 85
Calculation steps:
[( 85 - 815 ) ÷ 815] x 100 = -89.57%
Formula
Percentage change = [(85 - 815) / 815] x 100
Subtract the new number by the original number
85 - 815 = -730
-730 ÷ 815 = -0.8957055214723927
-0.8957055214723927 x 100 = -89.57%