-81.76% is the change from 850 to 155
Calculation steps:
[( 155 - 850 ) ÷ 850] x 100 = -81.76%
Formula
Percentage change = [(155 - 850) / 850] x 100
Subtract the new number by the original number
155 - 850 = -695
-695 ÷ 850 = -0.8176470588235294
-0.8176470588235294 x 100 = -81.76%