-64.31% is the change from 255 to 91
Calculation steps:
[( 91 - 255 ) ÷ 255] x 100 = -64.31%
Formula
Percentage change = [(91 - 255) / 255] x 100
Subtract the new number by the original number
91 - 255 = -164
-164 ÷ 255 = -0.6431372549019608
-0.6431372549019608 x 100 = -64.31%