$$\left. \begin{array} { l } { 3 x - 2 y + 7 z = 5 } \\ { 7 x + y + 9 z = 6 } \\ { 3 x + 3 y - 7 z = 0 } \end{array} \right.$$
$x=1$
$y=-1$
$z=0$
