Using elementary row operations to solve intersection of two planes The question I am struggling with is the following:
Solve the following using elementary row operations, and interpret each system of equations geometrically:
\begin{align*}
x - 3y + 2z &= 8\\
3x - 9y + 2z &= 4
\end{align*}
The answer given in the book is $x = -2+3t, y = t, z = 5$, and the planes meet in a line.
I put this in matrix form, so 
$$\left(\begin{array}{c c c|c}
1 & -3 & 2 & 8\\
3 & -9 & 2 & 4
\end{array}\right)
$$
Then I subtracted R1 from R2
$$\left(\begin{array}{c c c|c}
1 & -3 & 2 & 8\\
2 & -6 & 0 & -4
\end{array}\right)
$$
Then R1 - $\frac{1}{2}$R2
$$\left(\begin{array}{c c c|c}
0 & 0 & 2 & 10\\
-2 & -6 & 0 & -4
\end{array}\right)
$$
So I got that $2z =10$, so $z = 5$, but I am stumped on how to continue. How can I get $x$ and $y$ and interpret the results in terms of plane intersection?

$2z = 10$, so $z =  5$.
$2x - 6y = -4 \Rightarrow2x = -4 + 6y \Rightarrow x = -2 + 3y$. Let $y = t$, we get $x = -2 + 3t$, $y = t$, $z = 5$, as desired.
