2. Выполните действия: 1) \(\frac{5}{26} + \frac{11}{26} - \frac{7}{26}\); 2) 5\(\frac{8}{21} - 2\frac{3}{21} + 1\frac{5}{21}\); 3) 1 - \(\frac{15}{17}\); 4) 6\frac{4}{11} - 3\frac{7}{11}\.

1) \(\frac{5}{26} + \frac{11}{26} - \frac{7}{26} = \frac{5+11-7}{26} = \frac{16-7}{26} = \frac{9}{26}\).

2) \(5\frac{8}{21} - 2\frac{3}{21} + 1\frac{5}{21} = (5-2+1) + (\frac{8}{21} - \frac{3}{21} + \frac{5}{21}) = 4 + \frac{8-3+5}{21} = 4 + \frac{10}{21} = 4\frac{10}{21}\).

3) \(1 - \frac{15}{17} = \frac{17}{17} - \frac{15}{17} = \frac{17-15}{17} = \frac{2}{17}\).

4) \(6\frac{4}{11} - 3\frac{7}{11} = 6\frac{4}{11} - 3\frac{7}{11} = 5\frac{15}{11} - 3\frac{7}{11} = (5-3) + (\frac{15}{11} - \frac{7}{11}) = 2 + \frac{15-7}{11} = 2 + \frac{8}{11} = 2\frac{8}{11}\).

Ответ: 1) \(\frac{9}{26}\); 2) \(4\frac{10}{21}\); 3) \(\frac{2}{17}\); 4) \(2\frac{8}{11}\)