-20.39% is the change from 255 to 203
Calculation steps:
[( 203 - 255 ) ÷ 255] x 100 = -20.39%
Formula
Percentage change = [(203 - 255) / 255] x 100
Subtract the new number by the original number
203 - 255 = -52
-52 ÷ 255 = -0.20392156862745098
-0.20392156862745098 x 100 = -20.39%