Answer
$x=4$ and $x=2$
Work Step by Step
Put all terms on the left side.
Note than when a term is moved over to the other side of an equation, its sign changes to its opposite.
\begin{align*}
3x^2-18x+24&=0\\
\end{align*}
Factor out $3$:
\begin{align*}
3(x^2-6x+8)&=0
\end{align*}
Factor the trinomial:
\begin{align*}
3(x-4)(x-2)&=0
\end{align*}
Use the Zero-Product Property by equating each factor with a variable to zero, then solve each equation:
\begin{align*}
x-4&=0 &\text{or}& &x-2=0\\
x&=4 &\text{or}& &x=2
\end{align*}