641. Выполните действия: a) 3/4 : 5/6 + 2 1/2 * 2/5 - 1 : 1 1/6; б) 2 3/4 : (1 1/2 - 2/5) + (3/4 + 5/6) : 3 1/6; в) (2/15 + 7/12) * 30/43 - 2 : 2 1/2 * 5/32; г) (3 1/2 : 4 2/3 + 4 2/3 : 3 1/2) * 4 4/5; д) (11 5/11 - 8 21/22) : 1 2/3; e) ((1 1/2)^3 - 3/4) : 7/8.

641. Выполните действия:

1. a) $$\frac{3}{4} : \frac{5}{6} + 2 \frac{1}{2} \cdot \frac{2}{5} - 1 : 1 \frac{1}{6} = \frac{3}{4} \cdot \frac{6}{5} + \frac{5}{2} \cdot \frac{2}{5} - 1 : \frac{7}{6} = \frac{3}{4} \cdot \frac{6}{5} + \frac{5}{2} \cdot \frac{2}{5} - 1 \cdot \frac{6}{7} = \frac{18}{20} + \frac{10}{10} - \frac{6}{7} = \frac{9}{10} + 1 - \frac{6}{7} = \frac{9}{10} + \frac{10}{10} - \frac{6}{7} = \frac{19}{10} - \frac{6}{7} = \frac{19 \cdot 7}{70} - \frac{6 \cdot 10}{70} = \frac{133}{70} - \frac{60}{70} = \frac{73}{70} = 1 \frac{3}{70};$$
2. б) $$2 \frac{3}{4} : (1 \frac{1}{2} - \frac{2}{5}) + (\frac{3}{4} + \frac{5}{6}) : 3 \frac{1}{6} = \frac{11}{4} : (\frac{3}{2} - \frac{2}{5}) + (\frac{3}{4} + \frac{5}{6}) : \frac{19}{6} = \frac{11}{4} : (\frac{3 \cdot 5}{10} - \frac{2 \cdot 2}{10}) + (\frac{3 \cdot 3}{12} + \frac{5 \cdot 2}{12}) : \frac{19}{6} = \frac{11}{4} : (\frac{15}{10} - \frac{4}{10}) + (\frac{9}{12} + \frac{10}{12}) : \frac{19}{6} = \frac{11}{4} : \frac{11}{10} + \frac{19}{12} : \frac{19}{6} = \frac{11}{4} \cdot \frac{10}{11} + \frac{19}{12} \cdot \frac{6}{19} = \frac{11 \cdot 10}{4 \cdot 11} + \frac{19 \cdot 6}{12 \cdot 19} = \frac{10}{4} + \frac{6}{12} = \frac{5}{2} + \frac{1}{2} = \frac{5}{2} + \frac{1}{2} = \frac{6}{2} = 3;$$
3. в) $$\left(\frac{2}{15} + \frac{7}{12}\right) \cdot \frac{30}{43} - 2 : 2 \frac{1}{2} \cdot \frac{5}{32} = \left(\frac{2 \cdot 4}{60} + \frac{7 \cdot 5}{60}\right) \cdot \frac{30}{43} - 2 : \frac{5}{2} \cdot \frac{5}{32} = \left(\frac{8}{60} + \frac{35}{60}\right) \cdot \frac{30}{43} - 2 \cdot \frac{2}{5} \cdot \frac{5}{32} = \frac{43}{60} \cdot \frac{30}{43} - \frac{4}{5} \cdot \frac{5}{32} = \frac{43 \cdot 30}{60 \cdot 43} - \frac{4 \cdot 5}{5 \cdot 32} = \frac{30}{60} - \frac{4}{32} = \frac{1}{2} - \frac{1}{8} = \frac{4}{8} - \frac{1}{8} = \frac{3}{8};$$
4. г) $$\left(3 \frac{1}{2} : 4 \frac{2}{3} + 4 \frac{2}{3} : 3 \frac{1}{2}\right) \cdot 4 \frac{4}{5} = \left(\frac{7}{2} : \frac{14}{3} + \frac{14}{3} : \frac{7}{2}\right) \cdot \frac{24}{5} = \left(\frac{7}{2} \cdot \frac{3}{14} + \frac{14}{3} \cdot \frac{2}{7}\right) \cdot \frac{24}{5} = \left(\frac{7 \cdot 3}{2 \cdot 14} + \frac{14 \cdot 2}{3 \cdot 7}\right) \cdot \frac{24}{5} = \left(\frac{3}{4} + \frac{4}{3}\right) \cdot \frac{24}{5} = \left(\frac{3 \cdot 3}{12} + \frac{4 \cdot 4}{12}\right) \cdot \frac{24}{5} = \left(\frac{9}{12} + \frac{16}{12}\right) \cdot \frac{24}{5} = \frac{25}{12} \cdot \frac{24}{5} = \frac{25 \cdot 24}{12 \cdot 5} = \frac{5 \cdot 5 \cdot 2 \cdot 12}{12 \cdot 5} = 5 \cdot 2 = 10;$$
5. д) $$\left(11 \frac{5}{11} - 8 \frac{21}{22}\right) : 1 \frac{2}{3} = \left(\frac{126}{11} - \frac{197}{22}\right) : \frac{5}{3} = \left(\frac{126 \cdot 2}{22} - \frac{197}{22}\right) : \frac{5}{3} = \left(\frac{252}{22} - \frac{197}{22}\right) : \frac{5}{3} = \frac{55}{22} : \frac{5}{3} = \frac{55}{22} \cdot \frac{3}{5} = \frac{55 \cdot 3}{22 \cdot 5} = \frac{11 \cdot 5 \cdot 3}{2 \cdot 11 \cdot 5} = \frac{3}{2} = 1 \frac{1}{2};$$
6. е) $$\left(\left(1 \frac{1}{2}\right)^3 - \frac{3}{4}\right) : \frac{7}{8} = \left(\left(\frac{3}{2}\right)^3 - \frac{3}{4}\right) : \frac{7}{8} = \left(\frac{27}{8} - \frac{3}{4}\right) : \frac{7}{8} = \left(\frac{27}{8} - \frac{3 \cdot 2}{8}\right) : \frac{7}{8} = \left(\frac{27}{8} - \frac{6}{8}\right) : \frac{7}{8} = \frac{21}{8} : \frac{7}{8} = \frac{21}{8} \cdot \frac{8}{7} = \frac{21 \cdot 8}{8 \cdot 7} = \frac{3 \cdot 7 \cdot 8}{8 \cdot 7} = 3.$$

Ответ: a) $$1 \frac{3}{70}$$; б) $$3$$; в) $$\frac{3}{8}$$; г) $$10$$; д) $$1 \frac{1}{2}$$; е) $$3$$.