-5% is the change from 40 to 38
Calculation steps:
[( 38 - 40 ) ÷ 40] x 100 = -5%
Formula
Percentage change = [(38 - 40) / 40] x 100
Subtract the new number by the original number
38 - 40 = -2
-2 ÷ 40 = -0.05
-0.05 x 100 = -5%
Example