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

1) 2\(\frac{5}{21}\) - 2\(\frac{4}{21}\) + 1\(\frac{1}{21}\) = (2 - 2 + 1) + (\(\frac{5}{21}\) - \(\frac{4}{21}\) + \(\frac{1}{21}\)) = 1 + \(\frac{2}{21}\) = \(\frac{21}{21}\) + \(\frac{2}{21}\) = \(\frac{23}{21}\) = 1\(\frac{2}{21}\);

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

3) 1\(\frac{15}{17}\) = \(\frac{1 \cdot 17 + 15}{17}\) = \(\frac{17 + 15}{17}\) = \(\frac{32}{17}\) = 1\(\frac{15}{17}\);

4) 6\(\frac{4}{11}\) - 3\(\frac{7}{11}\) = (6 - 3) + (\(\frac{4}{11}\) - \(\frac{7}{11}\)) = 3 - \(\frac{3}{11}\) = \(\frac{33}{11}\) - \(\frac{3}{11}\) = \(\frac{30}{11}\) = 2\(\frac{8}{11}\);

5) \(\frac{2}{3}\) + \(\frac{4}{5}\) = \(\frac{2 \cdot 5}{3 \cdot 5}\) + \(\frac{4 \cdot 3}{5 \cdot 3}\) = \(\frac{10}{15}\) + \(\frac{12}{15}\) = \(\frac{22}{15}\) = 1\(\frac{7}{15}\);

6) \(\frac{3}{4}\) \cdot \(\frac{3}{8}\) = \(\frac{3 \cdot 3}{4 \cdot 8}\) = \(\frac{9}{32}\).