Краткое пояснение: Решаем примеры на деление и умножение дробей.
1) \[\frac{1}{2} : \frac{1}{3} = \frac{1}{2} \cdot \frac{3}{1} = \frac{3}{2} = 1\frac{1}{2}\]
2) \[\frac{5}{7} : \frac{2}{3} = \frac{5}{7} \cdot \frac{3}{2} = \frac{15}{14} = 1\frac{1}{14}\]
3) \[\frac{1}{2} : 4 = \frac{1}{2} \cdot \frac{1}{4} = \frac{1}{8}\]
4) \[:\frac{2}{3} : 4 = \frac{2}{3} \cdot \frac{1}{4} = \frac{2}{12} = \frac{1}{6}\]
5) \[: 2 : \frac{1}{4} = 2 \cdot \frac{4}{1} = 8\]
6) \[: \frac{4}{15} : \frac{2}{5} = \frac{4}{15} \cdot \frac{5}{2} = \frac{20}{30} = \frac{2}{3}\]
7) \[: \frac{2}{3} : \frac{3}{5} = \frac{2}{3} \cdot \frac{5}{3} = \frac{10}{9} = 1\frac{1}{9}\]
8) \[: \frac{7}{8} : \frac{7}{8} = 1\]
9) \[: \frac{3}{8} : \frac{5}{7} = \frac{3}{8} \cdot \frac{7}{5} = \frac{21}{40}\]
10) \[: \frac{1}{5} : \frac{3}{4} = \frac{1}{5} \cdot \frac{4}{3} = \frac{4}{15}\]
11) \[: 3 \frac{1}{7} : 2 = \frac{22}{7} \cdot \frac{1}{2} = \frac{22}{14} = \frac{11}{7} = 1 \frac{4}{7}\]
12) \[: 3 : \frac{1}{2} = 3 \cdot \frac{2}{1} = 6\]
13) \[: 4 \frac{1}{7} : 1 \frac{1}{3} = \frac{29}{7} : \frac{4}{3} = \frac{29}{7} \cdot \frac{3}{4} = \frac{87}{28} = 3 \frac{3}{28}\]
14) \[: 10 \frac{1}{3} : 2 \frac{2}{3} = \frac{31}{3} : \frac{8}{3} = \frac{31}{3} \cdot \frac{3}{8} = \frac{31}{8} = 3 \frac{7}{8}\]
15) \[: \frac{4}{15} : 3 = \frac{4}{15} \cdot \frac{1}{3} = \frac{4}{45}\]
16) \[: \frac{4}{15} : \frac{3}{5} = \frac{4}{15} \cdot \frac{5}{3} = \frac{20}{45} = \frac{4}{9}\]
17) \[: 4 \frac{3}{4} : 3 = \frac{19}{4} \cdot \frac{1}{3} = \frac{19}{12} = 1 \frac{7}{12}\]
18) \[: 1 : \frac{3}{11} = 1 \cdot \frac{11}{3} = \frac{11}{3} = 3 \frac{2}{3}\]
19) \[: 3 \frac{1}{4} : 1 = \frac{13}{4} : 1 = \frac{13}{4} = 3 \frac{1}{4}\]
20) \[: 3 \frac{15}{33} : 1 \frac{1}{51} = \frac{114}{33} : \frac{52}{51} = \frac{114}{33} \cdot \frac{51}{52} = \frac{5814}{1716} = \frac{969}{286} = 3 \frac{111}{286}\]
Ответ: смотри решение выше