Solve for \(x\), \(y\) and \(z\) the equations:
\[\begin{align*}
2x-y+z&{}=0,\\
3y+z&{}=0,\\
x+y+az&{}=b,
\end{align*}\]

where \(a\) and \(b\) are constants and \(a \neq 1\).

What does the second equation tell us that \(z\) is?

Now what does the first equation tell us that \(x\) is?

Now what does the third equation say?