Answer
$\left[\begin{array}{ccc}
3-x & -1 & -1-w\\
5-z & -1-r & -3
\end{array}\right]$
Work Step by Step
$A=\left[\begin{array}{lll}
1 & -1 & 0\\
0 & 2 & 1
\end{array}\right],\quad B=\left[\begin{array}{lll}
3 & 0 & -1\\
5 & -1 & 1
\end{array}\right],\quad C=\left[\begin{array}{lll}
x & 1 & w\\
z & r & 4
\end{array}\right]$
$(A-B)_{ij}=A_{ij}-B_{ij}$
ijth entry of the difference $=$ difference of the ijth entries
------------
$B-C=\left[\begin{array}{lll}
3-x & 0-1 & -1-w\\
5-z & -1-r & 1-4
\end{array}\right]=\left[\begin{array}{lll}
3-x & -1 & -1-w\\
5-z & -1-r & -3
\end{array}\right]$
