-80% is the change from 495 to 99
Calculation steps:
[( 99 - 495 ) ÷ 495] x 100 = -80%
Formula
Percentage change = [(99 - 495) / 495] x 100
Subtract the new number by the original number
99 - 495 = -396
-396 ÷ 495 = -0.8
-0.8 x 100 = -80%
Example