Answer
$x=-1$
Work Step by Step
$6-x=2x+9$ $\longrightarrow$addition property of equality
$6-x+x-9=2x+9+x-9$ $\longrightarrow$combine like terms
$-3=3x$ $\longrightarrow$multiplication property of equality
$-3\div3=3x\div3$ $\longrightarrow$simplify
$-1=x$
