Worked Solution #4 of 5, increasing in difficulty.

Expand the following:

\begin{align} \quad\quad\quad\quad\quad\quad\quad\quad\Large (3x+5)\color{#0000FF} {(3x-4)}\\ \\ &\cssId{Step1}{\Large =\color{#0000FF} { 3x}(3x+5) \color{#0000FF} {-4}(3x+5)}\\ \\ &\cssId{Step2}{\Large = 9x^2 + 15x - 12x - 20}\\ \\ &\cssId{Step3}{\Large = 9x^2 +3x - 20}\\ \\ \end{align}