462 Выполните действия: a) 7:4⋅9; 9 3 б) 5:8:2; 7 21 8 в) 1⋅3:1; 21 9 9 г) 5:6:1.

a) $$ 7\frac{2}{9} : 4\frac{1}{3} \cdot 9 = \frac{65}{9} : \frac{13}{3} \cdot 9 = \frac{65}{9} \cdot \frac{3}{13} \cdot 9 = \frac{65 \cdot 3 \cdot 9}{9 \cdot 13} = \frac{5 \cdot 3 \cdot 9}{9} = 5 \cdot 3 = 15 $$.

Ответ: 15

б) $$ 5\frac{3}{7} : \frac{8}{21} : 2\frac{3}{8} = \frac{38}{7} : \frac{8}{21} : \frac{19}{8} = \frac{38}{7} \cdot \frac{21}{8} \cdot \frac{8}{19} = \frac{38 \cdot 21 \cdot 8}{7 \cdot 8 \cdot 19} = \frac{2 \cdot 3 \cdot 1}{1 \cdot 1 \cdot 1} = 6$$.

Ответ: 6

в) $$ 1\frac{11}{21} \cdot 3\frac{8}{9} : 1\frac{7}{9} = \frac{32}{21} \cdot \frac{35}{9} : \frac{16}{9} = \frac{32}{21} \cdot \frac{35}{9} \cdot \frac{9}{16} = \frac{32 \cdot 35 \cdot 9}{21 \cdot 9 \cdot 16} = \frac{2 \cdot 5 \cdot 1}{1 \cdot 1 \cdot 1} = 10$$.

Ответ: 10

г) $$ \frac{5}{6} : \frac{6}{11} : 1\frac{1}{11} = \frac{5}{6} : \frac{6}{11} : \frac{12}{11} = \frac{5}{6} \cdot \frac{11}{6} \cdot \frac{11}{12} = \frac{5 \cdot 11 \cdot 11}{6 \cdot 6 \cdot 12} = \frac{605}{432} = 1\frac{173}{432}$$.

Ответ: $$1\frac{173}{432}$$