-90.37% is the change from 831 to 80
Calculation steps:
[( 80 - 831 ) ÷ 831] x 100 = -90.37%
Formula
Percentage change = [(80 - 831) / 831] x 100
Subtract the new number by the original number
80 - 831 = -751
-751 ÷ 831 = -0.9037304452466908
-0.9037304452466908 x 100 = -90.37%