-60% is the change from 15 to 6
Calculation steps:
[( 6 - 15 ) ÷ 15] x 100 = -60%
Formula
Percentage change = [(6 - 15) / 15] x 100
Subtract the new number by the original number
6 - 15 = -9
-9 ÷ 15 = -0.6
-0.6 x 100 = -60%
Example