Вычислите: а) \(\frac{2}{81} + \frac{4}{9}\); б) \(\frac{3}{56} - \frac{5}{8}\); в) \(\frac{7}{18} + \frac{3}{4}\); г) \(\frac{3}{5} - \frac{1}{3}\).

1. \(\frac{2}{81}+\frac{4}{9}=\frac{2}{81}+\frac{36}{81}=\frac{38}{81}\).
2. \(\frac{3}{56}-\frac{5}{8}=\frac{3}{56}-\frac{35}{56}=-\frac{32}{56}=-\frac{4}{7}\).
3. \(\frac{7}{18}+\frac{3}{4}=\frac{14}{36}+\frac{27}{36}=\frac{41}{36}=1\frac{5}{36}\).
4. \(\frac{3}{5}-\frac{1}{3}=\frac{9}{15}-\frac{5}{15}=\frac{4}{15}\).

Ответ: а) \(\frac{38}{81}\); б) \(-\frac{4}{7}\); в) \(1\frac{5}{36}\); г) \(\frac{4}{15}\).