-36.2% is the change from 815 to 520
Calculation steps:
[( 520 - 815 ) ÷ 815] x 100 = -36.2%
Formula
Percentage change = [(520 - 815) / 815] x 100
Subtract the new number by the original number
520 - 815 = -295
-295 ÷ 815 = -0.3619631901840491
-0.3619631901840491 x 100 = -36.2%