Let $$\mathbf{A}=\left[\begin{array}{rrr}3 & 0 & 4 \\-1 & 2 & 2 \\6 & 5 & -4\end{array}\right], \mathbf{B}=\left[\begin{array}{rrr}0 & -5 & -3 \\-5 & 2 & 4 \\-3 & 4 & 0\end{array}\right],$$
$$\mathbf{C}=\left[\begin{array}{ll}0 & 2 \\2 & 4 \\1 & 3\end{array}\right], \quad \mathbf{D}=\left[\begin{array}{rr}6 & 1 \\-4 & 7 \\-8 & 3\end{array}\right],$$ $$\mathbf{u}=\left[\begin{array}{r}2 \\0 \\-1\end{array}\right], \quad\mathbf{v}=\left[\begin{array}{r}-45 \\0.8 \\1.2\end{array}\right].$$
Find the following expressions or give reasons why they are undefined.
$$\mathbf{A}+\mathbf{C}-\mathbf{D}, \mathbf{C}-\mathbf{D}, \mathbf{D}-\mathbf{C}, \mathbf{B}+2 \mathbf{C}+4 \mathbf{D}$$