-39.22% is the change from 51 to 31
Calculation steps:
[( 31 - 51 ) ÷ 51] x 100 = -39.22%
Formula
Percentage change = [(31 - 51) / 51] x 100
Subtract the new number by the original number
31 - 51 = -20
-20 ÷ 51 = -0.39215686274509803
-0.39215686274509803 x 100 = -39.22%