\[\left\{ \begin{matrix}
x^{2} - 8x + 15 \leq 0 \\
3x - 13 \leq 0\ \ \ \ \ \ \ \ \ \ \\
\end{matrix} \right.\ \]
\[x^{2} - 8x + 15 \leq 0\]
\[D_{1} = 16 - 15 = 1\]
\[x_{1} = 4 + 1 = 5;\ \ x_{2} = 4 - 1 = 3.\]
\[(x - 3)(x - 5) \leq 0\]

\[3 \leq x \leq 5.\]
\[\left\{ \begin{matrix}
3 \leq x \leq 5 \\
3x \leq 13\ \ \ \ \\
\end{matrix} \right.\ \text{\ \ \ \ \ \ }\left\{ \begin{matrix}
3 \leq x \leq 5\ \ \ \ \ \\
x \leq \frac{13}{3} \leq 4\frac{1}{3} \\
\end{matrix} \right.\ \]
\[3 \leq x \leq 4\frac{1}{3}.\]
\[Ответ:3 \leq x \leq 4\frac{1}{3}.\]