First subtract 6y from both sides of the equation.
[tex]3x+6y-6y=18-6y\Longrightarrow 3x=18-6y[/tex]
Then divide both sides of the equation with 3.
[tex]3x=18-6y\Longrightarrow x=\dfrac{18-6y}{3}[/tex]
Which further simplifies to.
[tex]x=\dfrac{18}{3}-\dfrac{6y}{3}\Longrightarrow\boxed{6-2y}[/tex]
Hope this helps. I tried to made the steps very clear and easy.
r3t40
