-32.5% is the change from 120 to 81
Calculation steps:
[( 81 - 120 ) ÷ 120] x 100 = -32.5%
Formula
Percentage change = [(81 - 120) / 120] x 100
Subtract the new number by the original number
81 - 120 = -39
-39 ÷ 120 = -0.325
-0.325 x 100 = -32.5%
Example