-20.18% is the change from 550 to 439
Calculation steps:
[( 439 - 550 ) ÷ 550] x 100 = -20.18%
Formula
Percentage change = [(439 - 550) / 550] x 100
Subtract the new number by the original number
439 - 550 = -111
-111 ÷ 550 = -0.2018181818181818
-0.2018181818181818 x 100 = -20.18%