-90.6% is the change from 851 to 80
Calculation steps:
[( 80 - 851 ) ÷ 851] x 100 = -90.6%
Formula
Percentage change = [(80 - 851) / 851] x 100
Subtract the new number by the original number
80 - 851 = -771
-771 ÷ 851 = -0.9059929494712103
-0.9059929494712103 x 100 = -90.6%