-79.91% is the change from 851 to 171
Calculation steps:
[( 171 - 851 ) ÷ 851] x 100 = -79.91%
Formula
Percentage change = [(171 - 851) / 851] x 100
Subtract the new number by the original number
171 - 851 = -680
-680 ÷ 851 = -0.799059929494712
-0.799059929494712 x 100 = -79.91%