Выполните действия: a) $$\frac{14}{21} + \frac{11}{21} - \frac{8}{21}$$; б) $$7\frac{15}{16} - 2\frac{8}{16} + 5\frac{9}{16}$$; в) $$5\frac{9}{19} - 2$$

$$7\frac{15}{16} - 2\frac{8}{16} + 5\frac{9}{16} = (7 - 2 + 5) + (\frac{15}{16} - \frac{8}{16} + \frac{9}{16}) = 10 + \frac{15 - 8 + 9}{16} = 10 + \frac{16}{16} = 10 + 1 = 11$$ Ответ: 11