-20.38% is the change from 839 to 668
Calculation steps:
[( 668 - 839 ) ÷ 839] x 100 = -20.38%
Formula
Percentage change = [(668 - 839) / 839] x 100
Subtract the new number by the original number
668 - 839 = -171
-171 ÷ 839 = -0.20381406436233612
-0.20381406436233612 x 100 = -20.38%