31.28% is the change from 390 to 512
Calculation steps:
[( 512 - 390 ) ÷ 390] x 100 = 31.28%
Formula
Percentage change = [(512 - 390) / 390] x 100
Subtract the new number by the original number
512 - 390 = 122
122 ÷ 390 = 0.3128205128205128
0.3128205128205128 x 100 = 31.28%