-52.94% is the change from 255 to 120
Calculation steps:
[( 120 - 255 ) ÷ 255] x 100 = -52.94%
Formula
Percentage change = [(120 - 255) / 255] x 100
Subtract the new number by the original number
120 - 255 = -135
-135 ÷ 255 = -0.5294117647058824
-0.5294117647058824 x 100 = -52.94%