-40.91% is the change from 66 to 39
Calculation steps:
[( 39 - 66 ) ÷ 66] x 100 = -40.91%
Formula
Percentage change = [(39 - 66) / 66] x 100
Subtract the new number by the original number
39 - 66 = -27
-27 ÷ 66 = -0.4090909090909091
-0.4090909090909091 x 100 = -40.91%