-33.87% is the change from 815 to 539
Calculation steps:
[( 539 - 815 ) ÷ 815] x 100 = -33.87%
Formula
Percentage change = [(539 - 815) / 815] x 100
Subtract the new number by the original number
539 - 815 = -276
-276 ÷ 815 = -0.33865030674846625
-0.33865030674846625 x 100 = -33.87%