-20% is the change from 125 to 100
Calculation steps:
[( 100 - 125 ) ÷ 125] x 100 = -20%
Formula
Percentage change = [(100 - 125) / 125] x 100
Subtract the new number by the original number
100 - 125 = -25
-25 ÷ 125 = -0.2
-0.2 x 100 = -20%
Example