-21.96% is the change from 255 to 199
Calculation steps:
[( 199 - 255 ) ÷ 255] x 100 = -21.96%
Formula
Percentage change = [(199 - 255) / 255] x 100
Subtract the new number by the original number
199 - 255 = -56
-56 ÷ 255 = -0.2196078431372549
-0.2196078431372549 x 100 = -21.96%