39.64% is the change from 280 to 391
Calculation steps:
[( 391 - 280 ) ÷ 280] x 100 = 39.64%
Formula
Percentage change = [(391 - 280) / 280] x 100
Subtract the new number by the original number
391 - 280 = 111
111 ÷ 280 = 0.3964285714285714
0.3964285714285714 x 100 = 39.64%