8.51% is the change from 235 to 255
Calculation steps:
[( 255 - 235 ) ÷ 235] x 100 = 8.51%
Formula
Percentage change = [(255 - 235) / 235] x 100
Subtract the new number by the original number
255 - 235 = 20
20 ÷ 235 = 0.0851063829787234
0.0851063829787234 x 100 = 8.51%