4. Выполните действия: а) \(\frac{5}{6}+\frac{1}{4}\); б) \(\frac{3}{10}-1\frac{4}{5}\); в) \(5-3\frac{2}{7}\).

1. \(\frac{5}{6}+\frac{1}{4}=\frac{10}{12}+\frac{3}{12}=\frac{13}{12}=1\frac{1}{12}\).
2. \(\frac{3}{10}-1\frac{4}{5}=\frac{3}{10}-\frac{9}{5}=\frac{3}{10}-\frac{18}{10}=-\frac{15}{10}=-\frac{3}{2}=-1\frac{1}{2}\).
3. \(5-3\frac{2}{7}=5-\frac{23}{7}=\frac{35}{7}-\frac{23}{7}=\frac{12}{7}=1\frac{5}{7}\).

Ответ: а) \(1\frac{1}{12}\); б) \(-1\frac{1}{2}\); в) \(1\frac{5}{7}\).