\[0 < a < 3\ \ \ и\ \ - 1 < b < 0\]
\[- \left| \begin{matrix} 1 > \frac{1}{3}a > 0 \\ - 1 < b < 0 \\ \end{matrix} \right.\ \]
\[\text{\ \ \ \ }\overline{\begin{matrix} 2 > \frac{1}{3}a - b > 0 \\ 0 < \frac{a}{3} - b < 2 \\ \end{matrix}}\]