-18.07% is the change from 830 to 680
Calculation steps:
[( 680 - 830 ) ÷ 830] x 100 = -18.07%
Formula
Percentage change = [(680 - 830) / 830] x 100
Subtract the new number by the original number
680 - 830 = -150
-150 ÷ 830 = -0.18072289156626506
-0.18072289156626506 x 100 = -18.07%