-2.18% is the change from 550 to 538
Calculation steps:
[( 538 - 550 ) ÷ 550] x 100 = -2.18%
Formula
Percentage change = [(538 - 550) / 550] x 100
Subtract the new number by the original number
538 - 550 = -12
-12 ÷ 550 = -0.02181818181818182
-0.02181818181818182 x 100 = -2.18%