-50% is the change from 250 to 125
Calculation steps:
[( 125 - 250 ) ÷ 250] x 100 = -50%
Formula
Percentage change = [(125 - 250) / 250] x 100
Subtract the new number by the original number
125 - 250 = -125
-125 ÷ 250 = -0.5
-0.5 x 100 = -50%
Example