-16.75% is the change from 800 to 666
Calculation steps:
[( 666 - 800 ) ÷ 800] x 100 = -16.75%
Formula
Percentage change = [(666 - 800) / 800] x 100
Subtract the new number by the original number
666 - 800 = -134
-134 ÷ 800 = -0.1675
-0.1675 x 100 = -16.75%