28.97% is the change from 390 to 503
Calculation steps:
[( 503 - 390 ) ÷ 390] x 100 = 28.97%
Formula
Percentage change = [(503 - 390) / 390] x 100
Subtract the new number by the original number
503 - 390 = 113
113 ÷ 390 = 0.28974358974358977
0.28974358974358977 x 100 = 28.97%