Выполни действия в задании 607 а)

а) $$\frac{2}{3} \cdot \frac{6}{7} : \frac{4}{7} = \frac{2}{3} \cdot \frac{6}{7} \cdot \frac{7}{4} = \frac{2 \cdot 6 \cdot 7}{3 \cdot 7 \cdot 4} = \frac{2 \cdot 2 \cdot 3 \cdot 7}{3 \cdot 7 \cdot 4} = 1$$ б) $$\frac{11}{12} : \frac{7}{24} \cdot \frac{21}{22} = \frac{11}{12} \cdot \frac{24}{7} \cdot \frac{21}{22} = \frac{11 \cdot 24 \cdot 21}{12 \cdot 7 \cdot 22} = \frac{11 \cdot 2 \cdot 12 \cdot 3 \cdot 7}{12 \cdot 7 \cdot 2 \cdot 11} = 3$$ в) $$15/16 : 3/8 \cdot 3/4 = \frac{15}{16} : \frac{3}{8} \cdot \frac{3}{4} = \frac{15}{16} \cdot \frac{8}{3} \cdot \frac{3}{4} = \frac{15 \cdot 8 \cdot 3}{16 \cdot 3 \cdot 4} = \frac{5 \cdot 3 \cdot 8 \cdot 3}{2 \cdot 8 \cdot 3 \cdot 4} = \frac{15}{8}$$ г) $$13/14 : 7/25 : 13/25 = \frac{13}{14} : \frac{7}{25} : \frac{13}{25} = \frac{13}{14} \cdot \frac{25}{7} \cdot \frac{25}{13} = \frac{13 \cdot 25 \cdot 25}{14 \cdot 7 \cdot 13} = \frac{625}{98}$$ ж) $$(6\frac{1}{2} - 4\frac{1}{4}) : 2\frac{1}{2} = (\frac{13}{2} - \frac{17}{4}) : \frac{5}{2} = (\frac{26}{4} - \frac{17}{4}) : \frac{5}{2} = \frac{9}{4} : \frac{5}{2} = \frac{9}{4} \cdot \frac{2}{5} = \frac{9}{10}$$ з) $$(4\frac{8}{15} - 1\frac{1}{3}) \cdot 1\frac{7}{8} = (\frac{68}{15} - \frac{4}{3}) \cdot \frac{15}{8} = (\frac{68}{15} - \frac{20}{15}) \cdot \frac{15}{8} = \frac{48}{15} \cdot \frac{15}{8} = \frac{48 \cdot 15}{15 \cdot 8} = 6$$ и) $$(2\frac{2}{3} + 1\frac{5}{6}) : 1\frac{1}{2} = (\frac{8}{3} + \frac{11}{6}) : \frac{3}{2} = (\frac{16}{6} + \frac{11}{6}) : \frac{3}{2} = \frac{27}{6} : \frac{3}{2} = \frac{9}{2} \cdot \frac{2}{3} = 3$$ к) $$(3\frac{1}{6} - 2\frac{7}{15}) : 1\frac{2}{5} = (\frac{19}{6} - \frac{37}{15}) : \frac{7}{5} = (\frac{95}{30} - \frac{74}{30}) : \frac{7}{5} = \frac{21}{30} : \frac{7}{5} = \frac{7}{10} \cdot \frac{5}{7} = \frac{1}{2}$$ л) $$(1\frac{2}{3} + 2\frac{4}{9}) : (4\frac{26}{27} - 2\frac{2}{9}) = (\frac{5}{3} + \frac{22}{9}) : (\frac{134}{27} - \frac{20}{9}) = (\frac{15}{9} + \frac{22}{9}) : (\frac{134}{27} - \frac{60}{27}) = \frac{37}{9} : \frac{74}{27} = \frac{37}{9} \cdot \frac{27}{74} = \frac{3}{2}$$ м) $$(6\frac{1}{24} - \frac{2}{3}) : (3\frac{1}{2} + 1\frac{7}{8}) = (\frac{145}{24} - \frac{2}{3}) : (\frac{7}{2} + \frac{15}{8}) = (\frac{145}{24} - \frac{16}{24}) : (\frac{28}{8} + \frac{15}{8}) = \frac{129}{24} : \frac{43}{8} = \frac{43}{8} \cdot \frac{8}{43} = 1$$ e) $$(2\frac{2}{7} + 1\frac{1}{7}) \cdot 1\frac{1}{6} = (\frac{16}{7} + \frac{8}{7}) \cdot \frac{7}{6} = \frac{24}{7} \cdot \frac{7}{6} = \frac{24}{6} = 4$$