281. Выполните действия: a) \(\frac{6}{19} - \frac{3}{19} + \frac{15}{19}\); б) \(\frac{19}{21} - \frac{17}{21} + \frac{9}{21}\); в) \(\frac{25}{32} - \frac{6}{32} + \frac{19}{32}\).

а) \(\frac{6}{19} - \frac{3}{19} + \frac{15}{19} = \frac{6-3+15}{19} = \frac{18}{19}\)

Ответ: \(\frac{18}{19}\)

б) \(\frac{19}{21} - \frac{17}{21} + \frac{9}{21} = \frac{19-17+9}{21} = \frac{11}{21}\)

Ответ: \(\frac{11}{21}\)

в) \(\frac{25}{32} - \frac{6}{32} + \frac{19}{32} = \frac{25-6+19}{32} = \frac{38}{32} = \frac{19}{16} = 1\frac{3}{16}\)

Ответ: \(1\frac{3}{16}\)