-51.9% is the change from 815 to 392
Calculation steps:
[( 392 - 815 ) ÷ 815] x 100 = -51.9%
Formula
Percentage change = [(392 - 815) / 815] x 100
Subtract the new number by the original number
392 - 815 = -423
-423 ÷ 815 = -0.5190184049079755
-0.5190184049079755 x 100 = -51.9%