-27.06% is the change from 255 to 186
Calculation steps:
[( 186 - 255 ) ÷ 255] x 100 = -27.06%
Formula
Percentage change = [(186 - 255) / 255] x 100
Subtract the new number by the original number
186 - 255 = -69
-69 ÷ 255 = -0.27058823529411763
-0.27058823529411763 x 100 = -27.06%