-80% is the change from 800 to 160
Calculation steps:
[( 160 - 800 ) ÷ 800] x 100 = -80%
Formula
Percentage change = [(160 - 800) / 800] x 100
Subtract the new number by the original number
160 - 800 = -640
-640 ÷ 800 = -0.8
-0.8 x 100 = -80%
Example