135. Выполните действия: a) $$(1\frac{3}{5} + 2\frac{1}{5}):1\frac{9}{10} + (1\frac{7}{10} - \frac{4}{5}):\frac{3}{7}$$; б) $$6\frac{3}{8} \cdot 1\frac{7}{17} - 2\frac{3}{8}:1\frac{1}{4} + \frac{2}{5}$$.

a) $$(1\frac{3}{5} + 2\frac{1}{5}):1\frac{9}{10} + (1\frac{7}{10} - \frac{4}{5}):\frac{3}{7}$$;

1) $$1\frac{3}{5} + 2\frac{1}{5} = \frac{8}{5} + \frac{11}{5} = \frac{19}{5}$$;

2) $$1\frac{9}{10} = \frac{19}{10}$$;

3) $$\frac{19}{5} : \frac{19}{10} = \frac{19}{5} \cdot \frac{10}{19} = \frac{1}{1} \cdot \frac{2}{1} = 2$$;

4) $$1\frac{7}{10} - \frac{4}{5} = \frac{17}{10} - \frac{8}{10} = \frac{9}{10}$$;

5) $$\frac{9}{10} : \frac{3}{7} = \frac{9}{10} \cdot \frac{7}{3} = \frac{3}{10} \cdot \frac{7}{1} = \frac{21}{10}$$;

6) $$2 + \frac{21}{10} = \frac{20}{10} + \frac{21}{10} = \frac{41}{10} = 4\frac{1}{10}$$.

Ответ: $$4\frac{1}{10}$$

б) $$6\frac{3}{8} \cdot 1\frac{7}{17} - 2\frac{3}{8}:1\frac{1}{4} + \frac{2}{5}$$.

1) $$6\frac{3}{8} \cdot 1\frac{7}{17} = \frac{51}{8} \cdot \frac{24}{17} = \frac{3}{1} \cdot \frac{3}{1} = 9$$;

2) $$2\frac{3}{8}:1\frac{1}{4} = \frac{19}{8} : \frac{5}{4} = \frac{19}{8} \cdot \frac{4}{5} = \frac{19}{2} \cdot \frac{1}{5} = \frac{19}{10}$$;

3) $$9 - \frac{19}{10} = \frac{90}{10} - \frac{19}{10} = \frac{71}{10}$$;

4) $$\frac{71}{10} + \frac{2}{5} = \frac{71}{10} + \frac{4}{10} = \frac{75}{10} = \frac{15}{2} = 7\frac{1}{2}$$.

Ответ: $$7\frac{1}{2}$$