2. Выполнить действия с дробями.

Решение:

1. \( \frac{1}{5} + \frac{1}{3} = \frac{3+5}{15} = \frac{8}{15} \)
2. \( \frac{1}{2} + \frac{1}{8} = \frac{4+1}{8} = \frac{5}{8} \)
3. \( \frac{3}{4} + 2 = \frac{3}{4} + \frac{8}{4} = \frac{11}{4} \)
4. \( \frac{2}{3} - \frac{1}{6} = \frac{4-1}{6} = \frac{3}{6} = \frac{1}{2} \)
5. \( \frac{7}{12} - 1 = \frac{7-12}{12} = -\frac{5}{12} \)
6. \( \frac{4}{5} - \frac{9}{10} = \frac{8-9}{10} = -\frac{1}{10} \)
7. \( \frac{1}{3} - \frac{1}{2} = \frac{2-3}{6} = -\frac{1}{6} \)
8. \( 1 + \frac{2}{3} = \frac{3+2}{3} = \frac{5}{3} \)
9. \( \frac{8}{15} : 4 = \frac{8}{15 \cdot 4} = \frac{2}{15} \)
10. \( 3 \frac{3}{2} : \frac{7}{12} = \frac{9}{2} : \frac{7}{12} = \frac{9}{2} \cdot \frac{12}{7} = \frac{9 \cdot 6}{7} = \frac{54}{7} \)
11. \( -1 \frac{3}{4} : \left( -\frac{1}{4} \right) = -\frac{7}{4} : \left( -\frac{1}{4} \right) = \frac{7}{4} \cdot 4 = 7 \)
12. \( \frac{1}{4} \cdot 2 = \frac{2}{4} = \frac{1}{2} \)
13. \( - \frac{3}{4} \cdot \frac{4}{9} = -\frac{1}{3} \)
14. \( - \frac{1}{9} \cdot \frac{7}{35} = -\frac{1}{9} \cdot \frac{1}{5} = -\frac{1}{45} \)
15. \( 9 \frac{3}{4} \cdot \frac{4}{9} = \frac{39}{4} \cdot \frac{4}{9} = \frac{39}{9} = \frac{13}{3} \)
16. \( 9 \frac{7}{18} \cdot \left( -\frac{57}{64} \right) = \frac{169}{18} \cdot \left( -\frac{57}{64} \right) = -\frac{169 \cdot 19}{6 \cdot 64} = -\frac{3211}{384} \)
17. \( 2 \frac{3}{4} + 3 \frac{5}{7} = \frac{11}{4} + \frac{26}{7} = \frac{77+104}{28} = \frac{181}{28} \)
18. \( -4 \frac{2}{3} + 7 \frac{1}{2} = -\frac{14}{3} + \frac{15}{2} = \frac{-28+45}{6} = \frac{17}{6} \)
19. \( 4 \frac{1}{3} + \frac{2}{17} = \frac{13}{3} + \frac{2}{17} = \frac{221+6}{51} = \frac{227}{51} \)
20. \( -5 \frac{2}{5} + 4 \frac{1}{3} = -\frac{27}{5} + \frac{13}{3} = \frac{-81+65}{15} = -\frac{16}{15} \)
21. \( 6 \frac{1}{2} - 3 \frac{3}{4} = \frac{13}{2} - \frac{15}{4} = \frac{26-15}{4} = \frac{11}{4} \)
22. \( 2 \frac{1}{2} - 7 \frac{5}{6} = \frac{5}{2} - \frac{47}{6} = \frac{15-47}{6} = -\frac{32}{6} = -\frac{16}{3} \)
23. \( -4 \frac{2}{3} - 7 \frac{7}{9} = -\frac{14}{3} - \frac{70}{9} = \frac{-42-70}{9} = -\frac{112}{9} \)
24. \( 2 \frac{3}{4} \cdot 5 \frac{7}{33} = \frac{11}{4} \cdot \frac{172}{33} = \frac{1}{4} \cdot \frac{172}{3} = \frac{43}{3} \)
25. \( -3 \frac{1}{2} \cdot 2 \frac{2}{7} = -\frac{7}{2} \cdot \frac{16}{7} = -\frac{1}{2} \cdot 16 = -8 \)
26. \( 4 \frac{1}{5} : 7 \frac{1}{25} = \frac{21}{5} : \frac{176}{25} = \frac{21}{5} \cdot \frac{25}{176} = \frac{21 \cdot 5}{176} = \frac{105}{176} \)
27. \( -2 \frac{2}{3} - 3 \frac{5}{9} = -\frac{8}{3} - \frac{32}{9} = \frac{-24-32}{9} = -\frac{56}{9} \)

Ответ: 8/15; 5/8; 11/4; 1/2; -5/12; -1/10; -1/6; 5/3; 2/15; 54/7; 7; 1/2; -1/3; -1/45; 13/3; -3211/384; 181/28; 17/6; 227/51; -16/15; 11/4; -16/3; -112/9; 43/3; -8; 105/176; -56/9.