-16.56% is the change from 815 to 680
Calculation steps:
[( 680 - 815 ) ÷ 815] x 100 = -16.56%
Formula
Percentage change = [(680 - 815) / 815] x 100
Subtract the new number by the original number
680 - 815 = -135
-135 ÷ 815 = -0.1656441717791411
-0.1656441717791411 x 100 = -16.56%