-18.18% is the change from 11 to 9
Calculation steps:
[( 9 - 11 ) ÷ 11] x 100 = -18.18%
Formula
Percentage change = [(9 - 11) / 11] x 100
Subtract the new number by the original number
9 - 11 = -2
-2 ÷ 11 = -0.18181818181818182
-0.18181818181818182 x 100 = -18.18%