125% is the change from 40 to 90
Calculation steps:
[( 90 - 40 ) ÷ 40] x 100 = 125%
Formula
Percentage change = [(90 - 40) / 40] x 100
Subtract the new number by the original number
90 - 40 = 50
50 ÷ 40 = 1.25
1.25 x 100 = 125%
Example