20% is the change from 115 to 138
Calculation steps:
[( 138 - 115 ) ÷ 115] x 100 = 20%
Formula
Percentage change = [(138 - 115) / 115] x 100
Subtract the new number by the original number
138 - 115 = 23
23 ÷ 115 = 0.2
0.2 x 100 = 20%
Example