\[\left\{ \begin{matrix} 2 \cdot (5a - 4) - 3 \cdot (3 - 4b) = 5 \\ 6 \cdot (7b - 1) - (2 + 3a) = 31\ \ \\ \end{matrix} \right.\ \text{\ \ \ \ \ \ \ \ \ \ }\]
\[\left\{ \begin{matrix} 10a - 8 - 9 + 12b = 5 \\ 42b - 6 - 2 - 3a = 31 \\ \end{matrix} \right.\ \]
\[\left\{ \begin{matrix} 10a + 12b = 22\ \ \ \ | \cdot 7 \\ - 3a + 42b = 39\ \ \ \ | \cdot 2 \\ \end{matrix} \right.\ \text{\ \ \ \ \ \ \ \ \ \ \ }\]
\[\left\{ \begin{matrix} 70a + 84b = 154 \\ - 6a + 84b = 78 \\ \end{matrix} - \right.\ \]
\[\left\{ \begin{matrix} 76a = 76\ \ \ \ \\ b = \frac{39 + 3a}{42} \\ \end{matrix} \right.\ \text{\ \ \ \ \ \ \ \ \ \ \ \ }\]
\[\left\{ \begin{matrix} a = 1 \\ b = 1 \\ \end{matrix} \right.\ \]
\[Ответ:(1;1).\]