\[\left\{ \begin{matrix} 4x - 7y = - 12 \\ - 4x + 3y = 12 \\ \end{matrix} \right.\ ( + )\text{\ \ \ \ }\]
\[\left\{ \begin{matrix} - 4y = 0\ \ \ \ \ \ \ \ \ \\ 4x = 7y - 12 \\ \end{matrix} \right.\ \text{\ \ \ \ \ }\left\{ \begin{matrix} y = 0\ \ \ \ \ \ \ \ \\ 4x = - 12 \\ \end{matrix} \right.\ \text{\ \ \ \ \ \ }\]
\[\left\{ \begin{matrix} y = 0\ \ \\ x = - 3 \\ \end{matrix} \right.\ \text{\ \ \ \ \ \ }\]
\[Ответ:( - 3;0).\]