\[\boxed{\text{832.}\text{\ }\text{еуроки}\text{-}\text{ответы}\text{\ }\text{на}\text{\ }\text{пятёрку}}\]
\[(m;3) - решение\ системы.\]
\[\left\{ \begin{matrix} - 3x + y = 9\ \ \ \ \\ 2x - by = - 10 \\ \end{matrix} \right.\ \text{\ \ \ \ \ \ }\]
\[\ \left\{ \begin{matrix} - 3m + 3 = 9\ \ \ \ \ \ \ \ \\ - 2m - 3b = - 10 \\ \end{matrix} \right.\ \text{\ \ \ \ }\]
\[\left\{ \begin{matrix} 3m = - 6\ \ \ \ \ \ \ \ \ \ \ \ \ \\ 3b = - 2m + 10 \\ \end{matrix} \right.\ \]
\[\left\{ \begin{matrix} m = - 2 \\ 3b = 6\ \ \\ \end{matrix} \right.\ \text{\ \ \ \ \ \ \ }\left\{ \begin{matrix} m = - 2 \\ b = 2\ \ \ \ \ \\ \end{matrix} \right.\ \]
\[Ответ:при\ m = - 2;\ \ b = 2.\]