Solve the following system of equations using Gaussian elimination method. If there are no solutions, type "N" for both $x$, $y$ and $z$. If there are infinitely many solutions, type "z" for $z$, and expressions in terms of $z$ for $x$ and $y$. $$\begin{aligned} -6 x + 1 y - 6 z&=-2\\ 5 x + 9 y + 1 z&=4\\ 18 x - 3 y + 18 z&=2 \end{aligned}$$

$x=$ $y=$ $z=$