Ответ:

\(\frac{7}{8}+\frac{11}{16}=\frac{14}{16}+\frac{11}{16}=\frac{25}{16}\).

\(\frac{8}{15}:\frac{25}{16}=\frac{8}{15}\cdot\frac{16}{25}=\frac{128}{375}\).

Ответ: \(\frac{128}{375}\)