-78.9% is the change from 815 to 172
Calculation steps:
[( 172 - 815 ) ÷ 815] x 100 = -78.9%
Formula
Percentage change = [(172 - 815) / 815] x 100
Subtract the new number by the original number
172 - 815 = -643
-643 ÷ 815 = -0.7889570552147239
-0.7889570552147239 x 100 = -78.9%