-20.59% is the change from 102 to 81
Calculation steps:
[( 81 - 102 ) ÷ 102] x 100 = -20.59%
Formula
Percentage change = [(81 - 102) / 102] x 100
Subtract the new number by the original number
81 - 102 = -21
-21 ÷ 102 = -0.20588235294117646
-0.20588235294117646 x 100 = -20.59%