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

a) $$\frac{15}{19} - \frac{7}{19} + \frac{4}{19} = \frac{15-7+4}{19} = \frac{12}{19}$$ в) $$5 - 2\frac{4}{11} = 5 - \frac{2 \cdot 11 + 4}{11} = 5 - \frac{22+4}{11} = 5 - \frac{26}{11} = \frac{5 \cdot 11}{11} - \frac{26}{11} = \frac{55-26}{11} = \frac{29}{11} = 2\frac{7}{11}$$ б) $$7\frac{5}{14} + 3\frac{11}{14} = 7 + \frac{5}{14} + 3 + \frac{11}{14} = (7+3) + (\frac{5}{14} + \frac{11}{14}) = 10 + \frac{5+11}{14} = 10 + \frac{16}{14} = 10 + \frac{8}{7} = 10 + 1\frac{1}{7} = 11\frac{1}{7}$$ г) $$8\frac{2}{9} - 2\frac{4}{9} = 8 + \frac{2}{9} - 2 - \frac{4}{9} = (8-2) + (\frac{2}{9} - \frac{4}{9}) = 6 - \frac{2}{9} = \frac{6 \cdot 9}{9} - \frac{2}{9} = \frac{54-2}{9} = \frac{52}{9} = 5\frac{7}{9}$$