-74.12% is the change from 255 to 66
Calculation steps:
[( 66 - 255 ) ÷ 255] x 100 = -74.12%
Formula
Percentage change = [(66 - 255) / 255] x 100
Subtract the new number by the original number
66 - 255 = -189
-189 ÷ 255 = -0.7411764705882353
-0.7411764705882353 x 100 = -74.12%