\[\frac{7}{8}+\frac{11}{16}=\frac{14}{16}+\frac{11}{16}=\frac{25}{16}.\]
\[\frac{8}{15}\cdot\frac{25}{16}=\frac{25}{30}=\frac{5}{6}.\]
Ответ: \(\frac{5}{6}\).