\[0 < a < 1\ \ и\ \ - 5 < b < - 4\]
\[+ \left| \begin{matrix} 0 < 2a < 2 \\ - 15 < 3b < - 12 \\ \end{matrix} \right.\ \ \]
\[\overline{\ \ \ - 15 < 2a + 3b < - 10}\]