1. Выполни действия: a) $$\frac{15}{19} - \frac{7}{19} + \frac{4}{19}$$; б) $$7\frac{5}{14} + 3\frac{11}{14}$$; в) $$5 - 2\frac{4}{11}$$; г) $$8\frac{2}{9} - 2\frac{4}{9}$$.

Решение: a) $$\frac{15}{19} - \frac{7}{19} + \frac{4}{19} = \frac{15 - 7 + 4}{19} = \frac{8 + 4}{19} = \frac{12}{19}$$. б) $$7\frac{5}{14} + 3\frac{11}{14} = (7 + 3) + (\frac{5}{14} + \frac{11}{14}) = 10 + \frac{5 + 11}{14} = 10 + \frac{16}{14} = 10 + \frac{8}{7} = 10 + 1\frac{1}{7} = 11\frac{1}{7}$$. в) $$5 - 2\frac{4}{11} = 5 - (2 + \frac{4}{11}) = (5 - 2) - \frac{4}{11} = 3 - \frac{4}{11} = 2 + 1 - \frac{4}{11} = 2 + \frac{11}{11} - \frac{4}{11} = 2 + \frac{11 - 4}{11} = 2\frac{7}{11}$$. г) $$8\frac{2}{9} - 2\frac{4}{9} = (8 - 2) + (\frac{2}{9} - \frac{4}{9}) = 6 - \frac{2}{9} = 5 + 1 - \frac{2}{9} = 5 + \frac{9}{9} - \frac{2}{9} = 5 + \frac{7}{9} = 5\frac{7}{9}$$. Ответ: a) $$\frac{12}{19}$$; б) $$11\frac{1}{7}$$; в) $$2\frac{7}{11}$$; г) $$5\frac{7}{9}$$.