-95.29% is the change from 850 to 40
Calculation steps:
[( 40 - 850 ) ÷ 850] x 100 = -95.29%
Formula
Percentage change = [(40 - 850) / 850] x 100
Subtract the new number by the original number
40 - 850 = -810
-810 ÷ 850 = -0.9529411764705882
-0.9529411764705882 x 100 = -95.29%