-15.29% is the change from 255 to 216
Calculation steps:
[( 216 - 255 ) ÷ 255] x 100 = -15.29%
Formula
Percentage change = [(216 - 255) / 255] x 100
Subtract the new number by the original number
216 - 255 = -39
-39 ÷ 255 = -0.15294117647058825
-0.15294117647058825 x 100 = -15.29%