Ответ:

а) \(\frac{8}{7}:2=\frac{8}{7}\cdot\frac{1}{2}=\frac{4}{7}\).

б) \(\frac{10}{21}:5=\frac{10}{21}\cdot\frac{1}{5}=\frac{2}{21}\).

в) \(\frac{56}{13}:7=\frac{56}{13}\cdot\frac{1}{7}=\frac{8}{13}\).

г) \(\frac{27}{11}:18=\frac{27}{11}\cdot\frac{1}{18}=\frac{3}{22}\).

Ответ: а) \(\frac{4}{7}\); б) \(\frac{2}{21}\); в) \(\frac{8}{13}\); г) \(\frac{3}{22}\).