-18.27% is the change from 312 to 255
Calculation steps:
[( 255 - 312 ) ÷ 312] x 100 = -18.27%
Formula
Percentage change = [(255 - 312) / 312] x 100
Subtract the new number by the original number
255 - 312 = -57
-57 ÷ 312 = -0.18269230769230768
-0.18269230769230768 x 100 = -18.27%