Problem:
Add the two matrices
$\left(
\begin{array}{ccc}
 -3 & -7 & -4 \\
 3 & 0 & -6 \\
 1 & 0 & 9 \\
 1 & 9 & 5 \\
\end{array}
\right)$ and
$\left(
\begin{array}{ccc}
 -5 & -8 & 3 \\
 5 & -4 & -3 \\
 7 & 0 & -7 \\
 1 & 1 & 3 \\
\end{array}
\right)$
Answer:
$\left(
\begin{array}{ccc}
 -8 & -15 & -1 \\
 8 & -4 & -9 \\
 8 & 0 & 2 \\
 2 & 10 & 8 \\
\end{array}
\right)$
{'source': 'AMPS', 'file': 'amps/mathematica/linear_algebra/add/46166.txt'}