-40% is the change from 40 to 24
Calculation steps:
[( 24 - 40 ) ÷ 40] x 100 = -40%
Formula
Percentage change = [(24 - 40) / 40] x 100
Subtract the new number by the original number
24 - 40 = -16
-16 ÷ 40 = -0.4
-0.4 x 100 = -40%
Example