-17.67% is the change from 815 to 671
Calculation steps:
[( 671 - 815 ) ÷ 815] x 100 = -17.67%
Formula
Percentage change = [(671 - 815) / 815] x 100
Subtract the new number by the original number
671 - 815 = -144
-144 ÷ 815 = -0.17668711656441718
-0.17668711656441718 x 100 = -17.67%