Ответ:

  1. \(\frac{7}{9}+\frac{7}{18}=\frac{14}{18}+\frac{7}{18}=\frac{21}{18}=1\frac{1}{6}\).
  2. \(\frac{5}{6}-\frac{11}{36}=\frac{30}{36}-\frac{11}{36}=\frac{19}{36}\).
  3. \(\frac{5}{7}:\frac{7}{9}=\frac{5}{7}\cdot\frac{9}{7}=\frac{45}{49}\).
  4. \(1\frac{4}{7}:\frac{3}{7}=\frac{11}{7}\cdot\frac{7}{3}=\frac{11}{3}=3\frac{2}{3}\).
  5. \(\frac{13}{20}-\frac{4}{15}=\frac{39}{60}-\frac{16}{60}=\frac{23}{60}\).
  6. \(\frac{14}{15}:\frac{11}{12}=\frac{14}{15}\cdot\frac{12}{11}=\frac{56}{55}=1\frac{1}{55}\).

Ответ: а) \(1\frac{1}{6}\); б) \(\frac{19}{36}\); в) \(\frac{45}{49}\); г) \(3\frac{2}{3}\); д) \(\frac{23}{60}\); е) \(1\frac{1}{55}\).