-15% is the change from 80 to 68
Calculation steps:
[( 68 - 80 ) ÷ 80] x 100 = -15%
Formula
Percentage change = [(68 - 80) / 80] x 100
Subtract the new number by the original number
68 - 80 = -12
-12 ÷ 80 = -0.15
-0.15 x 100 = -15%
Example