Решите: (2/5 - 2/7) : 2/7 x 2/5 (5/6 - 3/10) : (3/10 + 2/15)

[latex]1) \frac{2}{5} - \frac{2}{7} = \frac{14-10}{35} = \frac{4}{35} \\ 2) \frac{4}{35} : \frac{2}{7} = \frac{4}{35} * \frac{7}{2} = \frac{2}{5} \\ 3) \frac{2}{5} * \frac{2}{5} = \frac{4}{25} \\ \\ \\ \\ 1) \frac{5}{6} - \frac{3}{10} = \frac{25-9}{30} = \frac{16}{30} \\ 2) \frac{3}{10} + \frac{2}{15} = \frac{9+4}{30} = \frac{13}{30} \\ 3) \frac{16}{30}: \frac{13}{30} = \frac{16}{30} * \frac{30}{13} = \frac{16}{13} =1 \frac{3}{13} [/latex]