-17.18% is the change from 809 to 670
Calculation steps:
[( 670 - 809 ) ÷ 809] x 100 = -17.18%
Formula
Percentage change = [(670 - 809) / 809] x 100
Subtract the new number by the original number
670 - 809 = -139
-139 ÷ 809 = -0.17181705809641531
-0.17181705809641531 x 100 = -17.18%