2. Выполните действия:

Решение:

1. \( \frac{2}{7} + \frac{3}{5} = \frac{10 + 21}{35} = \frac{31}{35} \)
2. \( \frac{1}{3} + \frac{3}{4} = \frac{4 + 9}{12} = \frac{13}{12} = 1\frac{1}{12} \)
3. \( \frac{7}{15} + \frac{13}{25} = \frac{35 + 39}{75} = \frac{74}{75} \)
4. \( \frac{5}{6} - \frac{1}{3} = \frac{5 - 2}{6} = \frac{3}{6} = \frac{1}{2} \)
5. \( 12 \frac{4}{19} = \frac{12 \cdot 19 + 4}{19} = \frac{228 + 4}{19} = \frac{232}{19} \)
6. \( \frac{14}{19} \)
7. \( \frac{18}{25} \cdot \frac{5}{9} = \frac{18 \cdot 5}{25 \cdot 9} = \frac{2 \cdot 1}{5 \cdot 1} = \frac{2}{5} \)
8. \( \frac{5}{22} \cdot 8 = \frac{5 \cdot 8}{22} = \frac{5 \cdot 4}{11} = \frac{20}{11} = 1\frac{9}{11} \)
9. \( \frac{7}{16} \)
10. \( \frac{2}{7} : \frac{5}{14} = \frac{2}{7} \cdot \frac{14}{5} = \frac{2 \cdot 2}{5} = \frac{4}{5} \)
11. \( \frac{15}{13} : \frac{8}{9} = \frac{15}{13} \cdot \frac{9}{8} = \frac{135}{104} = 1\frac{31}{104} \)
12. \( 16:9 = \frac{16}{9} = 1\frac{7}{9} \)