Solve the following fraction addition and subtraction problems.

Решение:

1. \( \frac{5}{21} + \frac{2}{21} = \frac{5+2}{21} = \frac{7}{21} \)
2. \( \frac{8}{15} + \frac{2}{15} = \frac{8+2}{15} = \frac{10}{15} \)
3. \( \frac{9}{35} + \frac{6}{35} = \frac{9+6}{35} = \frac{15}{35} \)
4. \( \frac{3}{22} + \frac{8}{22} = \frac{3+8}{22} = \frac{11}{22} \)
5. \( \frac{11}{12} - \frac{5}{12} = \frac{11-5}{12} = \frac{6}{12} \)
6. \( \frac{13}{15} - \frac{8}{15} = \frac{13-8}{15} = \frac{5}{15} \)
7. \( \frac{43}{50} - \frac{13}{50} = \frac{43-13}{50} = \frac{30}{50} \)
8. \( \frac{13}{24} - \frac{5}{24} = \frac{13-5}{24} = \frac{8}{24} \)