6. 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) Сократим дробь: \(\frac{32}{54}=\frac{16}{27}\). Тогда \(7-4\frac{16}{27}=2\frac{11}{27}\).

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) \(3\frac{27}{28}\).