Answer
$x=-1$ or $x=5$
Work Step by Step
$3x-|2x+1|=4 $ or $3x-|2x+1|=-4 $
Thus $3x-4=|2x+1| $ or $3x+4=|2x+1|$
Thus $3x-4=2x+1$ or $3x-4=-(2x+1)$ or $3x+4=2x+1$ or $3x+4=-(2x+1)$
Thus $x=5$ or $5x=3$ (but this is not a solution after substituting back) or $x=-3$ (not a solution after substituting back) or $x=-1$