42.5% is the change from 40 to 57
Calculation steps:
[( 57 - 40 ) ÷ 40] x 100 = 42.5%
Formula
Percentage change = [(57 - 40) / 40] x 100
Subtract the new number by the original number
57 - 40 = 17
17 ÷ 40 = 0.425
0.425 x 100 = 42.5%
Example