3. Найдите значение выражения: 7 1 1 1) 4-:—:—; 15 3 3 1 7 2) 4-:(-:—); 5 15 3 8 17 1 1 3) (5-:1—+1-):4-; 9 36 4 5 1 4 5 2 3 3 4) (2- +4-): 3--:—. 4 6 5 4 5

1) $$4\frac{1}{5} : \frac{7}{15} : \frac{1}{3} = \frac{21}{5} : \frac{7}{15} : \frac{1}{3} = \frac{21}{5} \cdot \frac{15}{7} : \frac{1}{3} = \frac{3}{1} \cdot \frac{3}{1} : \frac{1}{3} = 9 : \frac{1}{3} = 9 \cdot \frac{3}{1} = 27$$

2) $$4\frac{1}{5} : (\frac{7}{15} : \frac{1}{3}) = \frac{21}{5} : (\frac{7}{15} \cdot \frac{3}{1}) = \frac{21}{5} : \frac{7}{5} = \frac{21}{5} \cdot \frac{5}{7} = \frac{3}{1} \cdot \frac{1}{1} = 3$$

3) $$(5\frac{8}{9} : 1\frac{17}{36} + 1\frac{1}{4}) : 4\frac{1}{5} = (\frac{53}{9} : \frac{53}{36} + \frac{5}{4}) : \frac{21}{5} = (\frac{53}{9} \cdot \frac{36}{53} + \frac{5}{4}) : \frac{21}{5} = (4 + \frac{5}{4}) : \frac{21}{5} = (\frac{16}{4} + \frac{5}{4}) : \frac{21}{5} = \frac{21}{4} : \frac{21}{5} = \frac{21}{4} \cdot \frac{5}{21} = \frac{1}{4} \cdot \frac{5}{1} = \frac{5}{4} = 1\frac{1}{4}$$

4) $$(2\frac{1}{4} + 4\frac{5}{6}) : 3\frac{2}{5} - \frac{3}{4} \cdot \frac{3}{5} = (\frac{9}{4} + \frac{29}{6}) : \frac{17}{5} - \frac{9}{20} = (\frac{27}{12} + \frac{58}{12}) : \frac{17}{5} - \frac{9}{20} = \frac{85}{12} : \frac{17}{5} - \frac{9}{20} = \frac{85}{12} \cdot \frac{5}{17} - \frac{9}{20} = \frac{5}{12} \cdot \frac{5}{1} - \frac{9}{20} = \frac{25}{12} - \frac{9}{20} = \frac{125}{60} - \frac{27}{60} = \frac{98}{60} = \frac{49}{30} = 1\frac{19}{30}$$

Ответ: 1) 27; 2) 3; 3) $$1\frac{1}{4}$$; 4) $$1\frac{19}{30}$$