Answer
$A-5I_{3}=\begin{bmatrix}4&-1&3\\-8&2&-6\\-4&1&3\end{bmatrix}$
$(5I_{3})A=\begin{bmatrix}45&-5&15\\
-40&35&-30\\
-20&5&40
\end{bmatrix}$
Work Step by Step
$5I_{3}=\begin{bmatrix}5&0&0\\0&5&0\\0&0&5\end{bmatrix}$
$
\begin{align}
A-5I_{3}&=\begin{bmatrix}9-5&-1-0&3-0\\-8-0&7-5&-6-0\\-4-0&1-0&8-5\end{bmatrix}\\
&=\begin{bmatrix}4&-1&3\\-8&2&-6\\-4&1&3\end{bmatrix}
\end{align}
$
$
\begin{align}
(5I_{3})A &=\begin{bmatrix}(5I_{3})\begin{bmatrix}9\\-8\\-4\end{bmatrix}&(5I_{3})\begin{bmatrix}-1\\7\\1\end{bmatrix}&(5I_{3})\begin{bmatrix}3\\-6\\8\end{bmatrix}\end{bmatrix}\\
&=\begin{bmatrix}45&-5&15\\
-40&35&-30\\
-20&5&40
\end{bmatrix}
\end{align}
$
