1. Вычислите: a) $$1\frac{2}{5} + 3\frac{7}{15}$$; б) $$4\frac{3}{14} - 1\frac{2}{21}$$; в) $$3\frac{5}{6} + 2\frac{7}{15} - 1\frac{29}{30}$$.

Решение: a) $$1\frac{2}{5} + 3\frac{7}{15} = 1\frac{6}{15} + 3\frac{7}{15} = (1+3) + (\frac{6}{15} + \frac{7}{15}) = 4 + \frac{13}{15} = 4\frac{13}{15}$$. б) $$4\frac{3}{14} - 1\frac{2}{21} = 4\frac{9}{42} - 1\frac{4}{42} = (4-1) + (\frac{9}{42} - \frac{4}{42}) = 3 + \frac{5}{42} = 3\frac{5}{42}$$. в) $$3\frac{5}{6} + 2\frac{7}{15} - 1\frac{29}{30} = 3\frac{25}{30} + 2\frac{14}{30} - 1\frac{29}{30} = (3+2-1) + (\frac{25}{30} + \frac{14}{30} - \frac{29}{30}) = 4 + \frac{25+14-29}{30} = 4 + \frac{10}{30} = 4 + \frac{1}{3} = 4\frac{1}{3}$$. Ответ: a) $$4\frac{13}{15}$$; б) $$3\frac{5}{42}$$; в) $$4\frac{1}{3}$$.