CPM Homework Help : A2C Problem 7-200

Let $A$ and $B$ be the matrices defined below. Complete each of the following matrix arithmetic problems.

$A − B$
Answer (a):
$\begin{bmatrix} 9 & -1\\ 4 & 10 \end{bmatrix}$

$5A$

$AB$
Answer (c):
$\begin{bmatrix} -23& \ 8\\ -29&-16 \end{bmatrix}$

$BA$
Hint (d):
Refer to parts (a), (b),and (c).

$\left. \begin{array} { c } { A = \left[ \begin{array} { c c } { 4 } & { - 1 } \\ { 7 } & { 2 } \end{array} \right] } \\ { B = \left[ \begin{array} { c c } { - 5 } & { 0 } \\ { 3 } & { - 8 } \end{array} \right] } \end{array} \right.$