-20% is the change from 835 to 668
Calculation steps:
[( 668 - 835 ) ÷ 835] x 100 = -20%
Formula
Percentage change = [(668 - 835) / 835] x 100
Subtract the new number by the original number
668 - 835 = -167
-167 ÷ 835 = -0.2
-0.2 x 100 = -20%
Example