-20.09% is the change from 851 to 680
Calculation steps:
[( 680 - 851 ) ÷ 851] x 100 = -20.09%
Formula
Percentage change = [(680 - 851) / 851] x 100
Subtract the new number by the original number
680 - 851 = -171
-171 ÷ 851 = -0.2009400705052879
-0.2009400705052879 x 100 = -20.09%