-18.45% is the change from 840 to 685
Calculation steps:
[( 685 - 840 ) ÷ 840] x 100 = -18.45%
Formula
Percentage change = [(685 - 840) / 840] x 100
Subtract the new number by the original number
685 - 840 = -155
-155 ÷ 840 = -0.18452380952380953
-0.18452380952380953 x 100 = -18.45%