Chapter 4.2, Problem 52E

Each of the matrices in Problems 49-54 is the final matrix form for a system of two linear equations in the variables $x_1$ and $x_2$ Write the solution of the system.

$\left.\left[\left.\begin{array}{cc}1& -2\\ 0& 0\end{array}\right|\right.\begin{array}{c}7\\ -9\end{array}\right]$