Math Help - please need help matrix

please see the file attachedfor the question
thanks

2. This matrix is equivalent to this system:

$x + 3z = b$
$y = -2$
$az = 8$

The first question asks to set $a = 2$ and $b = 3$.

That is, solve:

$x + 3z = 3$
$y = -2$
$2z = 8$

The third equation tells us that $z = 4$. Substituting this result into the first equation, we get $x + 12 = 3$. So $x = -9$.

That's all. For part (a), the answer is that $x = -9$, $y = -2$, and $z = 4$.

Just do exactly the same steps to solve part (b).