\[\left\{ \begin{matrix} \frac{1}{3} \cdot (x - y) = 4\ \ | \cdot 3 \\ \frac{1}{4} \cdot (x + y) = 2\ \ | \cdot 4 \\ \end{matrix} \right.\ \text{\ \ \ \ \ \ \ \ \ }\]
\[\left\{ \begin{matrix} x - y = 12 \\ x + y = 8\ \ \ \\ \end{matrix} \right.\ \text{\ \ \ \ \ \ }\]
\[\left\{ \begin{matrix} x = y + 12\ \ \ \ \ \ \ \\ y + 12 + y = 8 \\ \end{matrix} \right.\ \]
\[\left\{ \begin{matrix} x = y + 12 \\ 2y = - 4\ \ \ \ \ \\ \end{matrix} \right.\ \text{\ \ \ \ \ \ \ \ }\]
\[\left\{ \begin{matrix} y = - 2\ \ \ \ \ \ \ \ \ \ \\ x = - 2 + 12 \\ \end{matrix} \right.\ \text{\ \ \ \ \ \ \ }\]
\[\left\{ \begin{matrix} y = - 2 \\ x = 10\ \\ \end{matrix} \right.\ \]
\[Ответ:(10;\ - 2).\]