Ответ:

\(\frac{4}{5}+\frac{4}{7}=\frac{48}{35}\).

\(3\frac{3}{8}+2\frac{11}{4}=\frac{27}{8}+\frac{19}{4}=\frac{65}{8}\).

\(\frac{48}{35}\cdot\frac{65}{8}=\frac{78}{7}=11\frac{1}{7}\).

Ответ: \(11\frac{1}{7}\)