-15% is the change from 40 to 34
Calculation steps:
[( 34 - 40 ) ÷ 40] x 100 = -15%
Formula
Percentage change = [(34 - 40) / 40] x 100
Subtract the new number by the original number
34 - 40 = -6
-6 ÷ 40 = -0.15
-0.15 x 100 = -15%
Example