-2% is the change from 550 to 539
Calculation steps:
[( 539 - 550 ) ÷ 550] x 100 = -2%
Formula
Percentage change = [(539 - 550) / 550] x 100
Subtract the new number by the original number
539 - 550 = -11
-11 ÷ 550 = -0.02
-0.02 x 100 = -2%
Example