-91.92% is the change from 990 to 80
Calculation steps:
[( 80 - 990 ) ÷ 990] x 100 = -91.92%
Formula
Percentage change = [(80 - 990) / 990] x 100
Subtract the new number by the original number
80 - 990 = -910
-910 ÷ 990 = -0.9191919191919192
-0.9191919191919192 x 100 = -91.92%