80% is the change from 40 to 72
Calculation steps:
[( 72 - 40 ) ÷ 40] x 100 = 80%
Formula
Percentage change = [(72 - 40) / 40] x 100
Subtract the new number by the original number
72 - 40 = 32
32 ÷ 40 = 0.8
0.8 x 100 = 80%
Example