-31.03% is the change from 29 to 20
Calculation steps:
[( 20 - 29 ) ÷ 29] x 100 = -31.03%
Formula
Percentage change = [(20 - 29) / 29] x 100
Subtract the new number by the original number
20 - 29 = -9
-9 ÷ 29 = -0.3103448275862069
-0.3103448275862069 x 100 = -31.03%