2. Вычислите: 1) 5/6 + 2/7; 2) 13/16 − 7/12; 3) 11/15 − 3/5; 4) 9/14 − 5/21; 5) 3/5 + 7/15; 6) 2/9 + 5/12.

1. \(\frac{5}{6}+\frac{2}{7}=\frac{35}{42}+\frac{12}{42}=\frac{47}{42}=1\frac{5}{42}\).
2. \(\frac{13}{16}-\frac{7}{12}=\frac{39}{48}-\frac{28}{48}=\frac{11}{48}\).
3. \(\frac{11}{15}-\frac{3}{5}=\frac{11}{15}-\frac{9}{15}=\frac{2}{15}\).
4. \(\frac{9}{14}-\frac{5}{21}=\frac{27}{42}-\frac{10}{42}=\frac{17}{42}\).
5. \(\frac{3}{5}+\frac{7}{15}=\frac{9}{15}+\frac{7}{15}=\frac{16}{15}=1\frac{1}{15}\).
6. \(\frac{2}{9}+\frac{5}{12}=\frac{8}{36}+\frac{15}{36}=\frac{23}{36}\).

Ответ: 1) \(1\frac{5}{42}\); 2) \(\frac{11}{48}\); 3) \(\frac{2}{15}\); 4) \(\frac{17}{42}\); 5) \(1\frac{1}{15}\); 6) \(\frac{23}{36}\).