607. Выполните действия:

а) $\frac{2}{3} \cdot \frac{6}{7} : \frac{4}{7} = \frac{2}{3} \cdot \frac{6}{7} \cdot \frac{7}{4} = \frac{2 \cdot 6 \cdot 7}{3 \cdot 7 \cdot 4} = 1$ б) $\frac{11}{12} : \frac{7}{24} \cdot \frac{21}{22} = \frac{11}{12} \cdot \frac{24}{7} \cdot \frac{21}{22} = \frac{11 \cdot 24 \cdot 21}{12 \cdot 7 \cdot 22} = 3$ в) $\frac{15}{16} : \frac{3}{8} \cdot \frac{3}{4} = \frac{15}{16} \cdot \frac{8}{3} \cdot \frac{3}{4} = \frac{15 \cdot 8 \cdot 3}{16 \cdot 3 \cdot 4} = \frac{15}{8} = 1\frac{7}{8}$ г) $\frac{13}{14} \cdot \frac{7}{25} : \frac{13}{25} = \frac{13}{14} \cdot \frac{7}{25} \cdot \frac{25}{13} = \frac{1}{2} = 0,5$ д) $3\frac{3}{4} \cdot (4\frac{1}{2} : 6\frac{3}{4}) = \frac{15}{4} \cdot (\frac{9}{2} \cdot \frac{4}{27}) = \frac{15}{4} \cdot \frac{2}{3} = 2\frac{1}{2}$ е) $(2\frac{2}{7} + 1\frac{1}{7}) \cdot 1\frac{1}{6} = 3\frac{3}{7} \cdot \frac{7}{6} = \frac{24}{7} \cdot \frac{7}{6} = 4$ ж) $(6\frac{1}{2} - 4\frac{1}{4}) : 2\frac{1}{2} = 2\frac{1}{4} : \frac{5}{2} = \frac{9}{4} \cdot \frac{2}{5} = \frac{9}{10} = 0,9$ з) $(4\frac{8}{15} - 1\frac{1}{3}) \cdot 1\frac{7}{8} = 3\frac{3}{15} \cdot \frac{15}{8} = \frac{16}{5} \cdot \frac{15}{8} = 6$ и) $(2\frac{2}{3} + 1\frac{5}{6}) : 1\frac{1}{2} = 4\frac{1}{2} : \frac{3}{2} = \frac{9}{2} \cdot \frac{2}{3} = 3$ к) $(3\frac{1}{6} - 2\frac{7}{15}) : 1\frac{2}{5} = \frac{7}{10} : \frac{7}{5} = \frac{7}{10} \cdot \frac{5}{7} = 0,5$ л) $(1\frac{2}{3} + 2\frac{4}{9}) : (4\frac{26}{27} - 2\frac{2}{9}) = 4\frac{1}{9} : 2\frac{20}{27} = \frac{37}{9} \cdot \frac{27}{74} = 1,5$ м) $(6\frac{1}{24} - \frac{2}{3}) : (3\frac{1}{2} + 1\frac{7}{8}) = 5\frac{3}{8} : 5\frac{3}{8} = 1$