Answer
$\left[\begin{array}{rr}
9 & 15\\
0 & -3\\
-3 & 3
\end{array}\right]$
Work Step by Step
$A=\left[\begin{array}{lll}
1 & -1 & 0\\
0 & 2 & -1
\end{array}\right],\quad B=\left[\begin{array}{lll}
3 & 0 & -1\\
5 & -1 & 1
\end{array}\right],\quad C=\left[\begin{array}{lll}
x & 1 & w\\
z & r & 4
\end{array}\right]$
$(B_{T})_{ij}=b_{ji}\quad $(rows in B are columns in $B^{T}$
$B^{T}=\left[\begin{array}{ll}
3 & 5\\
0 & -1\\
-1 & 1
\end{array}\right]$
$3B^{T}=\left[\begin{array}{ll}
3(3) & 3(5)\\
3(0) & 3(-1)\\
3(-1) & 3(1)
\end{array}\right]=\left[\begin{array}{ll}
9 & 15\\
0 & -3\\
-3 & 3
\end{array}\right]$
