\[\frac{x}{3} - \frac{y}{9} = 3\ \ \ | \cdot 9\]
\[3x - y = 27;\]
\[\frac{x}{6} + \frac{y}{3} = - 2\ \ \ \ | \cdot 6\]
\[x + 2y = - 12\]
\[\left\{ \begin{matrix} 3x - y = 27\ \text{\ \ \ \ }\ \ | \cdot 2 \\ x + 2y = - 12\ \ \ \ \ \ \ \ \ \ \ \\ \end{matrix} \right.\ \]
\[\left\{ \begin{matrix} 6x - 2y = 54\text{\ \ \ \ } \\ x + 2y = - 12\ \ \ \\ \end{matrix} \right.\ \ ( + )\]
\[7x = 42\]
\[x = 6.\]
\[y = 3x - 27 = 18 - 27 = - 9.\]
\[Ответ:(6; - 9).\]