97.5% is the change from 40 to 79
Calculation steps:
[( 79 - 40 ) ÷ 40] x 100 = 97.5%
Formula
Percentage change = [(79 - 40) / 40] x 100
Subtract the new number by the original number
79 - 40 = 39
39 ÷ 40 = 0.975
0.975 x 100 = 97.5%
Example