-35% is the change from 800 to 520
Calculation steps:
[( 520 - 800 ) ÷ 800] x 100 = -35%
Formula
Percentage change = [(520 - 800) / 800] x 100
Subtract the new number by the original number
520 - 800 = -280
-280 ÷ 800 = -0.35
-0.35 x 100 = -35%
Example