$\begin{bmatrix}3+1&1+1\\-2+(-2)&-1+(-3)\end{bmatrix}$

Double each entry in matrix A.

Multiply each row in matrix A by the column in matrix C.

$\begin{bmatrix}2(3)+4(-2)+(-1)(4)\\3(3)+0(-2)+2(4)\end{bmatrix}$

Do the rows of matrix C have the same number of entries as the columns of matrix A?

Multiply the rows of matrix B by the columns of matrix D.