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

1) \(\frac{5}{26} + \frac{11}{26} + \frac{7}{26} = \frac{5 + 11 + 7}{26} = \frac{23}{26}\)

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

Ответ: 1) \(\frac{23}{26}\); 2) \(4\frac{10}{21}\); 3) \(\frac{2}{17}\); 4) \(2\frac{8}{11}\)