Explanation:
[tex]\begin{gathered} 2a\text{ *a *a * 3a = 2 * 3 * a *a * a } \\ 6\text{ * a}^3\text{ = 6a}^3 \end{gathered}[/tex][tex]\begin{gathered} \text{b * 4b = 4 *b * b } \\ \text{4 * b}^2\text{ = 4b}^2 \end{gathered}[/tex]Put them together
[tex]2a*a*a*3a\text{ + b * 4b = 6a}^3+4b^2[/tex]