-21.57% is the change from 255 to 200
Calculation steps:
[( 200 - 255 ) ÷ 255] x 100 = -21.57%
Formula
Percentage change = [(200 - 255) / 255] x 100
Subtract the new number by the original number
200 - 255 = -55
-55 ÷ 255 = -0.21568627450980393
-0.21568627450980393 x 100 = -21.57%