-9.88% is the change from 800 to 721
Calculation steps:
[( 721 - 800 ) ÷ 800] x 100 = -9.88%
Formula
Percentage change = [(721 - 800) / 800] x 100
Subtract the new number by the original number
721 - 800 = -79
-79 ÷ 800 = -0.09875
-0.09875 x 100 = -9.88%