11) 2 13/16 : 4 3/8

\(2\frac{13}{16}=\frac{45}{16}\), \(4\frac{3}{8}=\frac{35}{8}\).

\(\frac{45}{16}:\frac{35}{8}=\frac{45}{16}\cdot\frac{8}{35}=\frac{9}{14}\).

Ответ: 9/14.