If
\[
P=
\begin{bmatrix}
0 & 1 & 2\\
2 & 3 & 4\\
1 & -1 & 0
\end{bmatrix}
\]
and
\[
Q=
\begin{bmatrix}
2 & -1 & 5\\
-4 & 2 & -4\\
2 & 2 & -4
\end{bmatrix},
\]
find the matrix product
\[
QP.
\]
Hence, solve the following system of linear equations using matrices:
\[
x-y=3,\qquad
2x+3y+4z=17,\qquad
y+2z=7.
\]