19.61% is the change from 255 to 305
Calculation steps:
[( 305 - 255 ) ÷ 255] x 100 = 19.61%
Formula
Percentage change = [(305 - 255) / 255] x 100
Subtract the new number by the original number
305 - 255 = 50
50 ÷ 255 = 0.19607843137254902
0.19607843137254902 x 100 = 19.61%