3. Найдите значение выражения: a)5$$\frac{8}{19}$$-2$$\frac{10}{19}$$; б)10$$\frac{19}{21}$$-(4$$\frac{16}{21}$$+3$$\frac{2}{21}$$)

а) 5$$\frac{8}{19}$$-2$$\frac{10}{19}$$ = (5 - 2) + ($$\frac{8}{19}$$ - $$\frac{10}{19}$$) = 3 - $$\frac{2}{19}$$ = 2 + 1 - $$\frac{2}{19}$$ = 2 + $$\frac{19}{19}$$ - $$\frac{2}{19}$$ = 2$$\frac{17}{19}$$

б) 10$$\frac{19}{21}$$-(4$$\frac{16}{21}$$+3$$\frac{2}{21}$$) = 10$$\frac{19}{21}$$ - 7$$\frac{18}{21}$$ = (10-7) + ($$\frac{19}{21}$$-$$\frac{18}{21}$$) = 3$$\frac{1}{21}$$

Ответ: а) 2$$\frac{17}{19}$$; б) 3$$\frac{1}{21}$$