Given the augmented matrix below, solve the associated system of equations. For your variables, use $x1$, $x2$, $x3$, $x4$, $x5$, $x6$, $x7$, and $x8$.
$$\displaystyle\left[\begin{array}{rrrrrrrr|r} 1 &5 &9 &1 &-5 &4 &-2 &2 &7 \cr 0 &0 &1 &-2 &4 &5 &1 &-6 &-2 \cr 0 &0 &0 &0 &1 &1 &-5 &0 &4 \cr 0 &0 &0 &0 &0 &1 &6 &7 &4 \cr \end{array}\right]$$
The solution is (,,, ,,,, )