-20% is the change from 85 to 68
Calculation steps:
[( 68 - 85 ) ÷ 85] x 100 = -20%
Formula
Percentage change = [(68 - 85) / 85] x 100
Subtract the new number by the original number
68 - 85 = -17
-17 ÷ 85 = -0.2
-0.2 x 100 = -20%
Example