5. Вычислите: 1) 1 9/12 + 3/12; 2) 7 − 4 32/54; 3) 15 23/28 − 11 24/28.

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

2. \(7-4\frac{32}{54}=7-4\frac{16}{27}=2\frac{27}{27}-\frac{16}{27}=2\frac{11}{27}\).

3. \(15\frac{23}{28}-11\frac{24}{28}=14\frac{51}{28}-11\frac{24}{28}=3\frac{27}{28}\).

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