Answer
$a.\qquad\left[\begin{array}{rrr}
5 & -2 & 5\\
1 & 1 & 0
\end{array}\right]$
$ b.\qquad$B+F is not defined.
Work Step by Step
$a.$
$B+C=\left[\begin{array}{lll}
3 & 1/2 & 5\\
1 & -1 & 3
\end{array}\right]+\left[\begin{array}{lll}
2 & -5/2 & 0\\
0 & 2 & -3
\end{array}\right]=\left[\begin{array}{lll}
5 & -2 & 5\\
1 & 1 & 0
\end{array}\right]$
$b.$
B is a 2$\times$3 matrix, F is a 3$\times$3 matrix.
Addition is defined only for matrices with the same dimension.
B+F is not defined.
