-50% is the change from 8 to 4
Calculation steps:
[( 4 - 8 ) ÷ 8] x 100 = -50%
Formula
Percentage change = [(4 - 8) / 8] x 100
Subtract the new number by the original number
4 - 8 = -4
-4 ÷ 8 = -0.5
-0.5 x 100 = -50%
Example