80% is the change from 15 to 27
Calculation steps:
[( 27 - 15 ) ÷ 15] x 100 = 80%
Formula
Percentage change = [(27 - 15) / 15] x 100
Subtract the new number by the original number
27 - 15 = 12
12 ÷ 15 = 0.8
0.8 x 100 = 80%
Example