-17.99% is the change from 817 to 670
Calculation steps:
[( 670 - 817 ) ÷ 817] x 100 = -17.99%
Formula
Percentage change = [(670 - 817) / 817] x 100
Subtract the new number by the original number
670 - 817 = -147
-147 ÷ 817 = -0.1799265605875153
-0.1799265605875153 x 100 = -17.99%