Ответ:

  1. \(2\frac{3}{4}+3,4=2,75+3,4=6,15\).
  2. \(4\frac{7}{25}-3,3=4,28-3,3=0,98\).
  3. \(7,2-6\frac{5}{6}=\frac{36}{5}-\frac{41}{6}=\frac{216-205}{30}=\frac{11}{30}=1\frac{11}{30}\).
  4. \(5\frac{7}{12}-1,6=5\frac{7}{12}-1\frac{3}{5}=3\frac{59}{60}\).

Ответ: а) 6,15; б) 0,98; в) 1\(\frac{11}{30}\); г) 3\(\frac{59}{60}\).