20% is the change from 15 to 18
Calculation steps:
[( 18 - 15 ) ÷ 15] x 100 = 20%
Formula
Percentage change = [(18 - 15) / 15] x 100
Subtract the new number by the original number
18 - 15 = 3
3 ÷ 15 = 0.2
0.2 x 100 = 20%
Example