30% is the change from 390 to 507
Calculation steps:
[( 507 - 390 ) ÷ 390] x 100 = 30%
Formula
Percentage change = [(507 - 390) / 390] x 100
Subtract the new number by the original number
507 - 390 = 117
117 ÷ 390 = 0.3
0.3 x 100 = 30%
Example