30.33% is the change from 399 to 520
Calculation steps:
[( 520 - 399 ) ÷ 399] x 100 = 30.33%
Formula
Percentage change = [(520 - 399) / 399] x 100
Subtract the new number by the original number
520 - 399 = 121
121 ÷ 399 = 0.3032581453634085
0.3032581453634085 x 100 = 30.33%