Answer
$x=-2$
Work Step by Step
$3x+4=x$ $\longrightarrow$addition property of equality
$3x+4-3x=x-3x$ $\longrightarrow$combine like terms
$4=-2x$ $\longrightarrow$multiplication property of equality
$4\div-2=-2x\div-2$ $\longrightarrow$simplify
$-2=x$
