-20.38% is the change from 834 to 664
Calculation steps:
[( 664 - 834 ) ÷ 834] x 100 = -20.38%
Formula
Percentage change = [(664 - 834) / 834] x 100
Subtract the new number by the original number
664 - 834 = -170
-170 ÷ 834 = -0.2038369304556355
-0.2038369304556355 x 100 = -20.38%