-50.61% is the change from 164 to 81
Calculation steps:
[( 81 - 164 ) ÷ 164] x 100 = -50.61%
Formula
Percentage change = [(81 - 164) / 164] x 100
Subtract the new number by the original number
81 - 164 = -83
-83 ÷ 164 = -0.5060975609756098
-0.5060975609756098 x 100 = -50.61%