-87.76% is the change from 809 to 99
Calculation steps:
[( 99 - 809 ) ÷ 809] x 100 = -87.76%
Formula
Percentage change = [(99 - 809) / 809] x 100
Subtract the new number by the original number
99 - 809 = -710
-710 ÷ 809 = -0.8776266996291718
-0.8776266996291718 x 100 = -87.76%