**a) \(\frac{1}{3} : \frac{3}{7} : \frac{1}{6}\)**
1. \(\frac{1}{3} : \frac{3}{7} = \frac{1}{3} \cdot \frac{7}{3} = \frac{7}{9}\)
2. \(\frac{7}{9} : \frac{1}{6} = \frac{7}{9} \cdot \frac{6}{1} = \frac{42}{9} = \frac{14}{3}\)
**Ответ: \(\frac{14}{3}\)**
**b) \(\frac{1}{18} : \frac{3}{5} : \frac{1}{3}\)**
1. \(\frac{1}{18} : \frac{3}{5} = \frac{1}{18} \cdot \frac{5}{3} = \frac{5}{54}\)
2. \(\frac{5}{54} : \frac{1}{3} = \frac{5}{54} \cdot \frac{3}{1} = \frac{15}{54} = \frac{5}{18}\)
**Ответ: \(\frac{5}{18}\)**
**c) \(\frac{1}{3} : \frac{3}{4} : \frac{1}{4}\)**
1. \(\frac{1}{3} : \frac{3}{4} = \frac{1}{3} \cdot \frac{4}{3} = \frac{4}{9}\)
2. \(\frac{4}{9} : \frac{1}{4} = \frac{4}{9} \cdot \frac{4}{1} = \frac{16}{9}\)
**Ответ: \(\frac{16}{9}\)**
**d) \(\frac{2}{3} : \frac{6}{11}\)**
\[\frac{2}{3} : \frac{6}{11} = \frac{2}{3} \cdot \frac{11}{6} = \frac{22}{18} = \frac{11}{9}\]
**Ответ: \(\frac{11}{9}\)**
**e) \((\frac{1}{5} + \frac{1}{20}) : \frac{4}{5}\)**
1. \(\frac{1}{5} + \frac{1}{20} = \frac{4}{20} + \frac{1}{20} = \frac{5}{20} = \frac{1}{4}\)
2. \(\frac{1}{4} : \frac{4}{5} = \frac{1}{4} \cdot \frac{5}{4} = \frac{5}{16}\)
**Ответ: \(\frac{5}{16}\)**
**f) \((\frac{1}{3} - \frac{1}{4}) : 12\)**
1. \(\frac{1}{3} - \frac{1}{4} = \frac{4}{12} - \frac{3}{12} = \frac{1}{12}\)
2. \(\frac{1}{12} : 12 = \frac{1}{12} \cdot \frac{1}{12} = \frac{1}{144}\)
**Ответ: \(\frac{1}{144}\)**