-38.16% is the change from 815 to 504
Calculation steps:
[( 504 - 815 ) ÷ 815] x 100 = -38.16%
Formula
Percentage change = [(504 - 815) / 815] x 100
Subtract the new number by the original number
504 - 815 = -311
-311 ÷ 815 = -0.3815950920245399
-0.3815950920245399 x 100 = -38.16%