-51.78% is the change from 815 to 393
Calculation steps:
[( 393 - 815 ) ÷ 815] x 100 = -51.78%
Formula
Percentage change = [(393 - 815) / 815] x 100
Subtract the new number by the original number
393 - 815 = -422
-422 ÷ 815 = -0.5177914110429448
-0.5177914110429448 x 100 = -51.78%