Answer
$$\begin{bmatrix}
-6&-2\\ 10&-2 \\ -8&15
\end{bmatrix}$$
Work Step by Step
We know that to add matrices, one must add each of the components to the corresponding components of the other matrix. For instance, in the form of a 2 by 2 matrix:
$\begin{bmatrix}
a & b \\
c&d
\end{bmatrix}$ + $\begin{bmatrix}
e& f \\
g&h
\end{bmatrix}$=$\begin{bmatrix}
a +e& b+f \\
c+g &d +h
\end{bmatrix}$
Note, while a two by two matrix is shown, this also works for matrices of all sizes. The same process also works for subtraction, multiplication, and division. Performing this operation for the given matrix, we obtain:
$$\begin{bmatrix}
-6&-2\\ 10&-2 \\ -8&15
\end{bmatrix}$$
