4. Вычислите: 1) 2 9/12+3/12; 2) 7−3 32/54; 3) 27 23/28−15 24/28.

1. \(2\frac{9}{12}+\frac{3}{12}=2\frac{12}{12}=3\).

2. Сократим дробь: \(3\frac{32}{54}=3\frac{16}{27}\).

   \(7-3\frac{16}{27}=6\frac{27}{27}-3\frac{16}{27}=3\frac{11}{27}\).

3. Займём единицу: \(27\frac{23}{28}=26\frac{51}{28}\).

   \(26\frac{51}{28}-15\frac{24}{28}=11\frac{27}{28}\).

Ответ: 1) 3; 2) \(3\frac{11}{27}\); 3) \(11\frac{27}{28}\).