-34.78% is the change from 391 to 255
Calculation steps:
[( 255 - 391 ) ÷ 391] x 100 = -34.78%
Formula
Percentage change = [(255 - 391) / 391] x 100
Subtract the new number by the original number
255 - 391 = -136
-136 ÷ 391 = -0.34782608695652173
-0.34782608695652173 x 100 = -34.78%