\begin{equation*}
\begin{split}
(2 + 3x)(3x - 12)& = 2\cdot 3x + 2\cdot (-12) + 3x\cdot 3x + 3x \cdot (-12)\\\\
(2 + 3x)(3x - 12)& = 6x - 24 + 9x^2 -36x\\\\
(2 + 3x)(3x - 12)& = 9x^2 + 6x - 36x - 24\\\\
(2 + 3x)(3x - 12)& = 9x^2 -30x - 24
\end{split}
\end{equation*}
