-50% is the change from 520 to 260
Calculation steps:
[( 260 - 520 ) ÷ 520] x 100 = -50%
Formula
Percentage change = [(260 - 520) / 520] x 100
Subtract the new number by the original number
260 - 520 = -260
-260 ÷ 520 = -0.5
-0.5 x 100 = -50%
Example