39.29% is the change from 280 to 390
Calculation steps:
[( 390 - 280 ) ÷ 280] x 100 = 39.29%
Formula
Percentage change = [(390 - 280) / 280] x 100
Subtract the new number by the original number
390 - 280 = 110
110 ÷ 280 = 0.39285714285714285
0.39285714285714285 x 100 = 39.29%