-90.01% is the change from 851 to 85
Calculation steps:
[( 85 - 851 ) ÷ 851] x 100 = -90.01%
Formula
Percentage change = [(85 - 851) / 851] x 100
Subtract the new number by the original number
85 - 851 = -766
-766 ÷ 851 = -0.900117508813161
-0.900117508813161 x 100 = -90.01%