-80% is the change from 855 to 171
Calculation steps:
[( 171 - 855 ) ÷ 855] x 100 = -80%
Formula
Percentage change = [(171 - 855) / 855] x 100
Subtract the new number by the original number
171 - 855 = -684
-684 ÷ 855 = -0.8
-0.8 x 100 = -80%
Example