-18.04% is the change from 255 to 209
Calculation steps:
[( 209 - 255 ) ÷ 255] x 100 = -18.04%
Formula
Percentage change = [(209 - 255) / 255] x 100
Subtract the new number by the original number
209 - 255 = -46
-46 ÷ 255 = -0.1803921568627451
-0.1803921568627451 x 100 = -18.04%