C-16 Вариант I. Выполните вычитание (1-2): 1. a) 1/5 - 2/5; б) 5/7 - 4/7; в) 7/9 - (-8/9).

a) \(\frac{1}{5} - \frac{2}{5} = \frac{1-2}{5} = \frac{-1}{5} = -\frac{1}{5}\) б) \(\frac{5}{7} - \frac{4}{7} = \frac{5-4}{7} = \frac{1}{7}\) в) \(\frac{7}{9} - \left(-\frac{8}{9}\right) = \frac{7}{9} + \frac{8}{9} = \frac{7+8}{9} = \frac{15}{9} = \frac{5}{3}\)