939 Используя приёмы, показанные в примерах 6 и 7, вычислите: a) \(-\frac{1}{2} - \frac{1}{4}\); б) \(-\frac{1}{15} + \frac{1}{10}\); в) \(-\frac{5}{8} - \frac{3}{4}\); г) \(\frac{2}{11} - \frac{3}{7}\); д) \(\frac{1}{3} - \frac{3}{4}\); e) \(-\frac{5}{6} + \frac{3}{2}\); ж) \(\frac{2}{9} - \frac{2}{3}\); з) \(-\frac{3}{5} - \frac{2}{3}\).

Решение: a) \(-\frac{1}{2} - \frac{1}{4} = -\frac{2}{4} - \frac{1}{4} = -\frac{3}{4}\) б) \(-\frac{1}{15} + \frac{1}{10} = -\frac{2}{30} + \frac{3}{30} = \frac{1}{30}\) в) \(-\frac{5}{8} - \frac{3}{4} = -\frac{5}{8} - \frac{6}{8} = -\frac{11}{8}\) г) \(\frac{2}{11} - \frac{3}{7} = \frac{14}{77} - \frac{33}{77} = -\frac{19}{77}\) д) \(\frac{1}{3} - \frac{3}{4} = \frac{4}{12} - \frac{9}{12} = -\frac{5}{12}\) e) \(-\frac{5}{6} + \frac{3}{2} = -\frac{5}{6} + \frac{9}{6} = \frac{4}{6} = \frac{2}{3}\) ж) \(\frac{2}{9} - \frac{2}{3} = \frac{2}{9} - \frac{6}{9} = -\frac{4}{9}\) з) \(-\frac{3}{5} - \frac{2}{3} = -\frac{9}{15} - \frac{10}{15} = -\frac{19}{15}\)