-18.19% is the change from 819 to 670
Calculation steps:
[( 670 - 819 ) ÷ 819] x 100 = -18.19%
Formula
Percentage change = [(670 - 819) / 819] x 100
Subtract the new number by the original number
670 - 819 = -149
-149 ÷ 819 = -0.18192918192918192
-0.18192918192918192 x 100 = -18.19%