\[\boxed{\text{1266.}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[mx - ny = 6;C(2;\ - 1);D( - 6;5)\]
\[2m + n = 6;\ - 6m - 5n = 6\]
\[\left\{ \begin{matrix} 2m + n = 6\ \ \ | \cdot 3 \\ - 6m - 5n = 6\ \ \ \ \\ \end{matrix} \right.\ \]
\[\left\{ \begin{matrix} 6m + 3n = 18 \\ - 6m - 5n = 6 \\ \end{matrix} \right.\ ( + )\]
\[- 2n = 24\]
\[n = - 12;\]
\[2m = 6 - n = 6 + 12 = 18\]
\[m = 9.\]
\[Ответ:при\ m = 9;n = - 12.\]