-97.65% is the change from 850 to 20
Calculation steps:
[( 20 - 850 ) ÷ 850] x 100 = -97.65%
Formula
Percentage change = [(20 - 850) / 850] x 100
Subtract the new number by the original number
20 - 850 = -830
-830 ÷ 850 = -0.9764705882352941
-0.9764705882352941 x 100 = -97.65%