\[\boxed{\mathbf{81}.}\]
\[1)\ \left\{ \begin{matrix} x - \frac{1}{2}y = - 1 \\ - 2x + y = 2\ \\ \end{matrix} \right.\ \text{\ \ \ \ }\left\{ \begin{matrix} \frac{1}{2}y = x + 1 \\ y = 2x + 2 \\ \end{matrix} \right.\ \text{\ \ \ }\]
\[\left\{ \begin{matrix} y = 2x + 2 \\ y = 2x + 2 \\ \end{matrix} \right.\ \]
\[Ответ:x - любое\ число.\]
\[2)\ \left\{ \begin{matrix} 2x + \frac{1}{3}y = 5\ \ \\ 4x - 3y = - 1 \\ \end{matrix} \right.\ \text{\ \ \ \ }\]
\[\left\{ \begin{matrix} \frac{1}{3}y = 5 - 2x \\ 3y = 4x + 1 \\ \end{matrix} \right.\ \text{\ \ \ \ }\left\{ \begin{matrix} y = 15 - 6x \\ y = \frac{4}{3}x + \frac{1}{3}\text{\ \ } \\ \end{matrix} \right.\ \]
\[Ответ:(2;3).\]