-18.93% is the change from 819 to 664
Calculation steps:
[( 664 - 819 ) ÷ 819] x 100 = -18.93%
Formula
Percentage change = [(664 - 819) / 819] x 100
Subtract the new number by the original number
664 - 819 = -155
-155 ÷ 819 = -0.18925518925518925
-0.18925518925518925 x 100 = -18.93%