33.59% is the change from 390 to 521
Calculation steps:
[( 521 - 390 ) ÷ 390] x 100 = 33.59%
Formula
Percentage change = [(521 - 390) / 390] x 100
Subtract the new number by the original number
521 - 390 = 131
131 ÷ 390 = 0.33589743589743587
0.33589743589743587 x 100 = 33.59%