Ответ:

  1. а) \(2\frac{3}{4}-1\frac{5}{6}=\frac{11}{4}-\frac{11}{6}=\frac{33-22}{12}=\frac{11}{12}\).
  2. б) \(4\frac{2}{5}+3\frac{5}{6}=7+\frac{12}{30}+\frac{25}{30}=8\frac{7}{30}\).

Ответ: а) \(\frac{11}{12}\); б) \(8\frac{7}{30}\).