-36.25% is the change from 800 to 510
Calculation steps:
[( 510 - 800 ) ÷ 800] x 100 = -36.25%
Formula
Percentage change = [(510 - 800) / 800] x 100
Subtract the new number by the original number
510 - 800 = -290
-290 ÷ 800 = -0.3625
-0.3625 x 100 = -36.25%