We can multiply polynomials by using a GRID METHOD
Write one of the polynomials across the top and the other down the left side.
$$ \begin{darray}{|c|c|c|c|}\hline & \color{blue}{6c^5} & \color{blue}{-2c^4} & \color{blue}{-2} \\ \hline \color{blue}{-11c^2} & & & \\ \hline \color{blue}{-15} & & & \\ \hline \end{darray} $$Fill in each empty box by multiplying the intersecting terms.
$$ \begin{darray}{|c|c|c|c|}\hline & \color{blue}{6c^5} & \color{blue}{-2c^4} & \color{blue}{-2} \\ \hline \color{blue}{-11c^2} & \color{orangered}{-66c^7} & \color{orangered}{22c^6} & \color{orangered}{22c^2} \\ \hline \color{blue}{-15} & \color{orangered}{-90c^5} & \color{orangered}{30c^4} & \color{orangered}{30} \\ \hline \end{darray} $$Combine like terms:
$$ -66c^7 + 22c^6-90c^5 + 22c^2 + 30c^4 + 30 = \\ -66c^7+22c^6-90c^5+30c^4+22c^2+30 $$