(a)[1]
With $M = \begin{pmatrix}5 & 1 \\ 2 & 3\end{pmatrix}$ and $N = \begin{pmatrix}4 & -2 \\ 3 & 0\end{pmatrix}$, find the matrix $M - N$.
(b)[2]
With $P = \begin{pmatrix}2 & 4 \\ c & -5\end{pmatrix}$, $Q = \begin{pmatrix}3 & 2 \\ -2 & d\end{pmatrix}$ and $PQ = \begin{pmatrix}-2 & 0 \\ 19 & 11\end{pmatrix}$, determine the value of $c$ and the value of $d$.