-79.8% is the change from 490 to 99
Calculation steps:
[( 99 - 490 ) ÷ 490] x 100 = -79.8%
Formula
Percentage change = [(99 - 490) / 490] x 100
Subtract the new number by the original number
99 - 490 = -391
-391 ÷ 490 = -0.7979591836734694
-0.7979591836734694 x 100 = -79.8%