Решение:

a) $$(1\frac{1}{5}+3\frac{3}{7}:12): 6 = (\frac{6}{5} + \frac{24}{7}:12):6 = (\frac{6}{5} + \frac{24}{7} \cdot \frac{1}{12}):6 = (\frac{6}{5} + \frac{2}{7}):6 = (\frac{42}{35} + \frac{10}{35}):6 = \frac{52}{35}:6 = \frac{52}{35} \cdot \frac{1}{6} = \frac{26}{35} \cdot \frac{1}{3} = \frac{26}{105}$$ Ответ: $$rac{26}{105}$$

б) $$(12\frac{4}{5}-4\frac{4}{7}): 8 = (\frac{64}{5}-\frac{32}{7}):8 = (\frac{448}{35} - \frac{160}{35}):8 = \frac{288}{35}:8 = \frac{288}{35} \cdot \frac{1}{8} = \frac{36}{35} \cdot \frac{1}{1} = \frac{36}{35} = 1\frac{1}{35}$$ Ответ: $$1\frac{1}{35}$$

в) $$(4\frac{1}{2} \cdot \frac{1}{7} \cdot \frac{5}{9}) \cdot 1\frac{1}{2} = (\frac{9}{2} \cdot \frac{1}{7} \cdot \frac{5}{9}) \cdot \frac{3}{2} = (\frac{1}{2} \cdot \frac{1}{7} \cdot \frac{5}{1}) \cdot \frac{3}{2} = \frac{5}{14} \cdot \frac{3}{2} = \frac{15}{28}$$ Ответ: $$\frac{15}{28}$$

г) $$(\frac{7}{8} \cdot \frac{2}{3} \cdot 1\frac{7}{8}): 5 = (\frac{7}{8} \cdot \frac{2}{3} \cdot \frac{15}{8}):5 = (\frac{7}{4} \cdot \frac{1}{3} \cdot \frac{15}{8}):5 = \frac{105}{96}:5 = \frac{35}{32} \cdot \frac{1}{5} = \frac{7}{32}$$ Ответ: $$\frac{7}{32}$$

д) $$14\frac{2}{5}:(\frac{3}{10} \cdot 3\frac{2}{3} \cdot \frac{2}{9}) = \frac{72}{5}:(\frac{3}{10} \cdot \frac{11}{3} \cdot \frac{2}{9}) = \frac{72}{5}:(\frac{1}{5} \cdot \frac{11}{1} \cdot \frac{2}{9}) = \frac{72}{5}:\frac{22}{45} = \frac{72}{5} \cdot \frac{45}{22} = \frac{36}{1} \cdot \frac{9}{11} = \frac{324}{11} = 29\frac{5}{11}$$ Ответ: $$29\frac{5}{11}$$

e) $$20\frac{4}{7}:(3\frac{3}{5} \cdot 1\frac{1}{7} \cdot 1\frac{1}{3}) = \frac{144}{7}:(\frac{18}{5} \cdot \frac{8}{7} \cdot \frac{4}{3}) = \frac{144}{7}:(\frac{6}{5} \cdot \frac{8}{7} \cdot \frac{4}{1}) = \frac{144}{7}:\frac{192}{35} = \frac{144}{7} \cdot \frac{35}{192} = \frac{3}{1} \cdot \frac{5}{4} = \frac{15}{4} = 3\frac{3}{4}$$ Ответ: $$3\frac{3}{4}$$