5. \(3\frac{5}{7}\cdot2\frac{5}{8}\cdot1\frac{11}{13}=\)

\(3\frac{5}{7}=\frac{26}{7}\), \(2\frac{5}{8}=\frac{21}{8}\), \(1\frac{11}{13}=\frac{24}{13}\).

\(\frac{26}{7}\cdot\frac{21}{8}\cdot\frac{24}{13}=\frac{26}{13}\cdot\frac{21}{7}\cdot\frac{24}{8}=2\cdot3\cdot3=18\).

Ответ: 18.