6. Вычислите: 1) $$1\frac{9}{12}+ \frac{3}{12}$$; 2) $$7-4\frac{32}{54}$$; 3) $$15\frac{23}{28}-11\frac{24}{28}$$.

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

Ответ: 2

2) $$7 - 4\frac{32}{54} = 6\frac{54}{54} - 4\frac{32}{54} = 2\frac{22}{54} = 2\frac{11}{27}$$

Ответ: $$2\frac{11}{27}$$

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

Ответ: $$3\frac{27}{28}$$