5) \(1\frac{31}{35}:(2-\frac{8}{9}:1\frac{19}{45})\).

\(\frac{8}{9}:1\frac{19}{45}=\frac{8}{9}:\frac{64}{45}=\frac{5}{8}\).

Скобки: \(2-\frac{5}{8}=\frac{11}{8}\).

\(1\frac{31}{35}:\frac{11}{8}=\frac{66}{35}\cdot\frac{8}{11}=\frac{48}{35}\).

Ответ: \(\frac{48}{35}=1\frac{13}{35}\)