a) $$\frac{7}{9} : \frac{7}{18} = \frac{7}{9} \cdot \frac{18}{7} = \frac{7 \cdot 18}{9 \cdot 7} = \frac{18}{9} = 2$$
б) $$\frac{1}{4} : \frac{1}{3} = \frac{1}{4} \cdot \frac{3}{1} = \frac{3}{4}$$
в) $$\frac{3}{4} : \frac{7}{9} = \frac{3}{4} \cdot \frac{9}{7} = \frac{3 \cdot 9}{4 \cdot 7} = \frac{27}{28}$$
г) $$\frac{3}{7} : \frac{1}{14} = \frac{3}{7} \cdot \frac{14}{1} = \frac{3 \cdot 14}{7 \cdot 1} = \frac{3 \cdot 2}{1 \cdot 1} = 6$$
д) $$\frac{6}{11} : 6 = \frac{6}{11} \cdot \frac{1}{6} = \frac{6 \cdot 1}{11 \cdot 6} = \frac{1}{11}$$
е) $$\frac{9}{13} : 3 = \frac{9}{13} \cdot \frac{1}{3} = \frac{9 \cdot 1}{13 \cdot 3} = \frac{3}{13}$$
ж) $$\frac{5}{7} : \frac{1}{7} = \frac{5}{7} \cdot \frac{7}{1} = \frac{5 \cdot 7}{7 \cdot 1} = 5$$
Ответ: а) 2; б) $$\frac{3}{4}$$; в) $$\frac{27}{28}$$; г) 6; д) $$\frac{1}{11}$$; е) $$\frac{3}{13}$$; ж) 5