-50% is the change from 132 to 66
Calculation steps:
[( 66 - 132 ) ÷ 132] x 100 = -50%
Formula
Percentage change = [(66 - 132) / 132] x 100
Subtract the new number by the original number
66 - 132 = -66
-66 ÷ 132 = -0.5
-0.5 x 100 = -50%
Example