\[\left\{ \begin{matrix} x - y = - 3 \\ x + 3y = 1 \\ \end{matrix} \right.\ \Longrightarrow \left\{ \begin{matrix} y = x + 3\ \ \\ 3y = 1 - x \\ \end{matrix} \right.\ \]
\[\left\{ \begin{matrix} y = x + 3\ \ \ \\ y = \frac{1}{3} - \frac{1}{3}x \\ \end{matrix} \right.\ \]
\[Ответ:( - 2;1).\]