1) Вычислите: \(\frac{5}{9}-\frac{4}{9}\); 2) \(\frac{4}{15}+\frac{1}{5}\); 3) \(\frac{5}{27}\cdot\frac{18}{35}\); 4) \(\frac{14}{27}:\frac{28}{81}\).

1. \(\frac{5}{9}-\frac{4}{9}=\frac{1}{9}\).
2. \(\frac{4}{15}+\frac{1}{5}=\frac{4}{15}+\frac{3}{15}=\frac{7}{15}\).
3. \(\frac{5}{27}\cdot\frac{18}{35}=\frac{2}{21}\).
4. \(\frac{14}{27}:\frac{28}{81}=\frac{14}{27}\cdot\frac{81}{28}=\frac{3}{2}\).

Ответ: 1) \(\frac{1}{9}\); 2) \(\frac{7}{15}\); 3) \(\frac{2}{21}\); 4) \(\frac{3}{2}\).