3. Выполните сложение или вычитание: 7/12 + 3/12; 3/7 + 2/7; 13/55 − 5/55; 11/18 − 7/18; 7/10 + 1/10; 15/8 − 7/8; 12/15 + 7/15; 45/100 + 35/100; 65/76 − 25/76; 4/5 − 3/5; 4/11 + 6/11; 7/8 − 5/8; 76/100 − 67/100; 6/13 + 7/13; 43/56 − 33/56; 6/23 + 20/23; 4/7 + 2/7; 3/4 + 3/4; 7 + 1/5; 3 − 4/7; 1 − 6/11; 1 + 3 5/7; 8 2/5 + 3; 7 − 4/9; 8 7/6 − 6; 4 + 1 3/5; 7 − 2 1/2.

1. \(\frac{7}{12}+\frac{3}{12}=\frac{10}{12}=\frac{5}{6}\)
2. \(\frac{3}{7}+\frac{2}{7}=\frac{5}{7}\)
3. \(\frac{13}{55}-\frac{5}{55}=\frac{8}{55}\)
4. \(\frac{11}{18}-\frac{7}{18}=\frac{4}{18}=\frac{2}{9}\)
5. \(\frac{7}{10}+\frac{1}{10}=\frac{8}{10}=\frac{4}{5}\)
6. \(\frac{15}{8}-\frac{7}{8}=\frac{8}{8}=1\)
7. \(\frac{12}{15}+\frac{7}{15}=\frac{19}{15}=1\frac{4}{15}\)
8. \(\frac{45}{100}+\frac{35}{100}=\frac{80}{100}=\frac{4}{5}\)
9. \(\frac{65}{76}-\frac{25}{76}=\frac{40}{76}=\frac{10}{19}\)
10. \(\frac{4}{5}-\frac{3}{5}=\frac{1}{5}\)
11. \(\frac{4}{11}+\frac{6}{11}=\frac{10}{11}\)
12. \(\frac{7}{8}-\frac{5}{8}=\frac{2}{8}=\frac{1}{4}\)
13. \(\frac{76}{100}-\frac{67}{100}=\frac{9}{100}\)
14. \(\frac{6}{13}+\frac{7}{13}=1\)
15. \(\frac{43}{56}-\frac{33}{56}=\frac{10}{56}=\frac{5}{28}\)
16. \(\frac{6}{23}+\frac{20}{23}=\frac{26}{23}=1\frac{3}{23}\)
17. \(\frac{4}{7}+\frac{2}{7}=\frac{6}{7}\)
18. \(\frac{3}{4}+\frac{3}{4}=\frac{6}{4}=1\frac{1}{2}\)
19. \(7+\frac{1}{5}=7\frac{1}{5}\)
20. \(3-\frac{4}{7}=2\frac{3}{7}\)
21. \(1-\frac{6}{11}=\frac{5}{11}\)
22. \(1+3\frac{5}{7}=4\frac{5}{7}\)
23. \(8\frac{2}{5}+3=11\frac{2}{5}\)
24. \(7-\frac{4}{9}=6\frac{5}{9}\)
25. \(8\frac{7}{6}-6=3\frac{1}{6}\)
26. \(4+1\frac{3}{5}=5\frac{3}{5}\)
27. \(7-2\frac{1}{2}=4\frac{1}{2}\)

Ответ: \(\frac{5}{6};\frac{5}{7};\frac{8}{55};\frac{2}{9};\frac{4}{5};1;1\frac{4}{15};\frac{4}{5};\frac{10}{19};\frac{1}{5};\frac{10}{11};\frac{1}{4};\frac{9}{100};1;\frac{5}{28};1\frac{3}{23};\frac{6}{7};1\frac{1}{2};7\frac{1}{5};2\frac{3}{7};\frac{5}{11};4\frac{5}{7};11\frac{2}{5};6\frac{5}{9};3\frac{1}{6};5\frac{3}{5};4\frac{1}{2}\).