Выполните действия: a) $$rac{16}{19} - \frac{11}{19} + \frac{4}{19}$$; б) $$6\frac{5}{13} + 2\frac{9}{13}$$; в) $$5 - 3\frac{6}{7}$$; г) $$7\frac{2}{9} - 3\frac{4}{9}$$.

1. a) $$\frac{16}{19} - \frac{11}{19} + \frac{4}{19} = \frac{16 - 11 + 4}{19} = \frac{9}{19}$$
2. б) $$6\frac{5}{13} + 2\frac{9}{13} = (6 + 2) + (\frac{5}{13} + \frac{9}{13}) = 8 + \frac{14}{13} = 8 + 1\frac{1}{13} = 9\frac{1}{13}$$
3. в) $$5 - 3\frac{6}{7} = 4\frac{7}{7} - 3\frac{6}{7} = (4 - 3) + (\frac{7}{7} - \frac{6}{7}) = 1 + \frac{1}{7} = 1\frac{1}{7}$$
4. г) $$7\frac{2}{9} - 3\frac{4}{9} = 6\frac{11}{9} - 3\frac{4}{9} = (6 - 3) + (\frac{11}{9} - \frac{4}{9}) = 3 + \frac{7}{9} = 3\frac{7}{9}$$

Ответ:

• а) $$\frac{9}{19}$$
• б) $$9\frac{1}{13}$$
• в) $$1\frac{1}{7}$$
• г) $$3\frac{7}{9}$$