-30.77% is the change from 13 to 9
Calculation steps:
[( 9 - 13 ) ÷ 13] x 100 = -30.77%
Formula
Percentage change = [(9 - 13) / 13] x 100
Subtract the new number by the original number
9 - 13 = -4
-4 ÷ 13 = -0.3076923076923077
-0.3076923076923077 x 100 = -30.77%