\left [ 
\begin{array}{ccc} 
\begin{array}{cc}
1 & -3 \\
a & 2 \\
4 & -3
\end{array} & 
\left |
\begin{array}{c}
4 \\
5 \\
b
\end{array}
\end{array}
\right ]\sim
\left [ 
\begin{array}{ccc} 
\begin{array}{cc}
1 & -3 \\
0 & 3a+2 \\
0 & 0
\end{array} & 
\left |
\begin{array}{c}
4 \\
-4a+5 \\
\frac{-9}{3a+2}\cdot (-4a+5)-16 + b
\end{array}
\end{array}
\right ].