Вычислите: а) 5/6 + 2/7; б) 11/25 − 3/10; в) 15/16 − 3/4; г) 3/20 + 7/15; д) 13/16 − 7/12; е) 9/14 + 5/21.

1. \(\frac{5}{6}+\frac{2}{7}=\frac{35}{42}+\frac{12}{42}=\frac{47}{42}=1\frac{5}{42}\).
2. \(\frac{11}{25}-\frac{3}{10}=\frac{22}{50}-\frac{15}{50}=\frac{7}{50}\).
3. \(\frac{15}{16}-\frac{3}{4}=\frac{15}{16}-\frac{12}{16}=\frac{3}{16}\).
4. \(\frac{3}{20}+\frac{7}{15}=\frac{9}{60}+\frac{28}{60}=\frac{37}{60}\).
5. \(\frac{13}{16}-\frac{7}{12}=\frac{39}{48}-\frac{28}{48}=\frac{11}{48}\).
6. \(\frac{9}{14}+\frac{5}{21}=\frac{27}{42}+\frac{10}{42}=\frac{37}{42}\).

Ответ: а) \(1\frac{5}{42}\); б) \(\frac{7}{50}\); в) \(\frac{3}{16}\); г) \(\frac{37}{60}\); д) \(\frac{11}{48}\); е) \(\frac{37}{42}\).