125% is the change from 20 to 45
Calculation steps:
[( 45 - 20 ) ÷ 20] x 100 = 125%
Formula
Percentage change = [(45 - 20) / 20] x 100
Subtract the new number by the original number
45 - 20 = 25
25 ÷ 20 = 1.25
1.25 x 100 = 125%
Example