Выполни действия: a) 5/6 + 1/4

a) $\frac{5}{6} + \frac{1}{4} = \frac{5 * 2}{6 * 2} + \frac{1 * 3}{4 * 3} = \frac{10}{12} + \frac{3}{12} = \frac{13}{12}$ б) $\frac{7}{8} - \frac{5}{6} = \frac{7 * 3}{8 * 3} - \frac{5 * 4}{6 * 4} = \frac{21}{24} - \frac{20}{24} = \frac{1}{24}$ в) $\frac{3}{10} - \frac{4}{15} = \frac{3 * 3}{10 * 3} - \frac{4 * 2}{15 * 2} = \frac{9}{30} - \frac{8}{30} = \frac{1}{30}$ г) $5 - 3\frac{2}{7} = 4\frac{7}{7} - 3\frac{2}{7} = 1\frac{5}{7}$ д) $\frac{4}{9} * \frac{3}{8} = \frac{4 * 3}{9 * 8} = \frac{12}{72} = \frac{1}{6}$ е) $\frac{5}{8} : \frac{9}{10} = \frac{5}{8} * \frac{10}{9} = \frac{5 * 10}{8 * 9} = \frac{50}{72} = \frac{25}{36}$ ж) $2\frac{6}{7} : 1\frac{3}{7} = \frac{2 * 7 + 6}{7} : \frac{1 * 7 + 3}{7} = \frac{20}{7} : \frac{10}{7} = \frac{20}{7} * \frac{7}{10} = \frac{20 * 7}{7 * 10} = \frac{140}{70} = 2$ з) $6\frac{3}{5} * 10 = \frac{6 * 5 + 3}{5} * 10 = \frac{33}{5} * 10 = \frac{33 * 10}{5} = \frac{330}{5} = 66$