Ответ:

  1. \(1-\frac{4}{9}=\frac{9}{9}-\frac{4}{9}=\frac{5}{9}\).
  2. \(1+1\frac{5}{6}=2\frac{5}{6}\).
  3. \(7-\frac{3}{8}=6\frac{8}{8}-\frac{3}{8}=6\frac{5}{8}\).
  4. \(4-3\frac{3}{4}=\frac{16}{4}-\frac{15}{4}=\frac{1}{4}\).

Ответ: а) \(\frac{5}{9}\); б) \(2\frac{5}{6}\); в) \(6\frac{5}{8}\); г) \(\frac{1}{4}\).