-16.5% is the change from 800 to 668
Calculation steps:
[( 668 - 800 ) ÷ 800] x 100 = -16.5%
Formula
Percentage change = [(668 - 800) / 800] x 100
Subtract the new number by the original number
668 - 800 = -132
-132 ÷ 800 = -0.165
-0.165 x 100 = -16.5%