Answer
$x=-2$
Work Step by Step
$3(x-4)=5x-8$ $\longrightarrow$distributive property
$3x-12=5x-8$ $\longrightarrow$addition property
$3x-12-3x+8=5x-8-3x+8$ $\longrightarrow$combinelike terms
$-4=2x$ $\longrightarrow$multiplication property
$-4\div2=2x\div2$ $\longrightarrow$simplify
$-2=x$