Г: 3/7 − 13/35; 8/15 + 2/25; 1/7 − 1/8; 3/8 + 7/72; 13/20 − 3/8; 1/6 + 7/10; 1/6 − 1/12; 2/25 + 1/9; 3/4 − 31/42; 7/12 + 3/20; 19/21 − 5/6; 34/45 − 7/10; 4/21 + 9/14; 4/9 + 17/63; 11/24 − 7/16.

Чтобы выполнить действия с дробями, приводим их к общему знаменателю, а затем складываем или вычитаем числители.

1. \(\frac{3}{7}-\frac{13}{35}=\frac{15}{35}-\frac{13}{35}=\frac{2}{35}\).
2. \(\frac{8}{15}+\frac{2}{25}=\frac{40}{75}+\frac{6}{75}=\frac{46}{75}\).
3. \(\frac{1}{7}-\frac{1}{8}=\frac{8}{56}-\frac{7}{56}=\frac{1}{56}\).
4. \(\frac{3}{8}+\frac{7}{72}=\frac{27}{72}+\frac{7}{72}=\frac{17}{36}\).
5. \(\frac{13}{20}-\frac{3}{8}=\frac{26}{40}-\frac{15}{40}=\frac{11}{40}\).
6. \(\frac{1}{6}+\frac{7}{10}=\frac{5}{30}+\frac{21}{30}=\frac{13}{15}\).
7. \(\frac{1}{6}-\frac{1}{12}=\frac{1}{12}\).
8. \(\frac{2}{25}+\frac{1}{9}=\frac{18}{225}+\frac{25}{225}=\frac{43}{225}\).
9. \(\frac{3}{4}-\frac{31}{42}=\frac{63}{84}-\frac{62}{84}=\frac{1}{84}\).
10. \(\frac{7}{12}+\frac{3}{20}=\frac{35}{60}+\frac{9}{60}=\frac{11}{15}\).
11. \(\frac{19}{21}-\frac{5}{6}=\frac{38}{42}-\frac{35}{42}=\frac{1}{14}\).
12. \(\frac{34}{45}-\frac{7}{10}=\frac{68}{90}-\frac{63}{90}=\frac{1}{18}\).
13. \(\frac{4}{21}+\frac{9}{14}=\frac{8}{42}+\frac{27}{42}=\frac{5}{6}\).
14. \(\frac{4}{9}+\frac{17}{63}=\frac{28}{63}+\frac{17}{63}=\frac{5}{7}\).
15. \(\frac{11}{24}-\frac{7}{16}=\frac{22}{48}-\frac{21}{48}=\frac{1}{48}\).