1) \(\frac{1}{4} : \frac{1}{4} \cdot \frac{1}{7} = 1 \cdot \frac{1}{7} = \frac{1}{7}\)
2) \(\frac{1}{3} : \frac{7}{8} : \frac{9}{14} = \frac{1}{3} \cdot \frac{8}{7} \cdot \frac{14}{9} = \frac{1 \cdot 8 \cdot 14}{3 \cdot 7 \cdot 9} = \frac{112}{189} = \frac{16}{27}\)
3) \(\frac{1}{3} : \frac{7}{8} : \frac{9}{14} = \frac{1}{3} \cdot \frac{8}{7} \cdot \frac{14}{9} = \frac{1 \cdot 8 \cdot 14}{3 \cdot 7 \cdot 9} = \frac{112}{189} = \frac{16}{27}\)
4) \(\frac{6}{7} : \frac{5}{7} \cdot \frac{4}{9} = \frac{6}{7} \cdot \frac{7}{5} \cdot \frac{4}{9} = \frac{6 \cdot 7 \cdot 4}{7 \cdot 5 \cdot 9} = \frac{168}{315} = \frac{8}{15}\)
Ответ: 1) \(\frac{1}{7}\); 2) \(\frac{16}{27}\); 3) \(\frac{16}{27}\); 4) \(\frac{8}{15}\)