49.09% is the change from 550 to 820
Calculation steps:
[( 820 - 550 ) ÷ 550] x 100 = 49.09%
Formula
Percentage change = [(820 - 550) / 550] x 100
Subtract the new number by the original number
820 - 550 = 270
270 ÷ 550 = 0.4909090909090909
0.4909090909090909 x 100 = 49.09%