6) 3 5/7 : 9/28 =

\(3\frac{5}{7}=\frac{26}{7}\).

\(\frac{26}{7}:\frac{9}{28}=\frac{26}{7}\cdot\frac{28}{9}=26\cdot\frac{4}{9}=\frac{104}{9}=11\frac{5}{9}\).

Ответ: \(11\frac{5}{9}\).