2. Найдите значение выражений. a) 6/19 + (8/19 - 3/19) б) 18 4/21 - (10/21 + 3/21)

а) \(\frac{6}{19} + (\frac{8}{19} - \frac{3}{19}) = \frac{6}{19} + \frac{5}{19} = \frac{11}{19}\) б) \(18\frac{4}{21} - (10\frac{10}{21} + 3\frac{3}{21}) = 18\frac{4}{21} - 13\frac{13}{21} = 17\frac{25}{21} - 13\frac{13}{21} = 4\frac{12}{21} = 4\frac{4}{7}\)