9). \(\frac{2}{3}:\frac{6}{7}:\frac{4}{7}\) 10). \(\frac{11}{12}:\frac{7}{24}\cdot\frac{21}{22}\)

9) \(\frac{2}{3}:\frac{6}{7}:\frac{4}{7}=\frac{2}{3}\cdot\frac{7}{6}\cdot\frac{7}{4}=\frac{2\cdot7\cdot7}{3\cdot6\cdot4}=\frac{98}{72}=\frac{49}{36}=1\frac{13}{36}\)

10) \(\frac{11}{12}:\frac{7}{24}\cdot\frac{21}{22}=\frac{11}{12}\cdot\frac{24}{7}\cdot\frac{21}{22}=\frac{11\cdot24\cdot21}{12\cdot7\cdot22}=\frac{5544}{1848}=3\)

Ответ: 9) \(1\frac{13}{36}\), 10) 3