50.91% is the change from 550 to 830
Calculation steps:
[( 830 - 550 ) ÷ 550] x 100 = 50.91%
Formula
Percentage change = [(830 - 550) / 550] x 100
Subtract the new number by the original number
830 - 550 = 280
280 ÷ 550 = 0.509090909090909
0.509090909090909 x 100 = 50.91%