1. Найдите значение выражения: a) 3-2 ; б) 6+2 ; B) 4+(5-3).

a) 3$$\frac{4}{7}$$-2$$\frac{3}{5}$$; б) 6$$\frac{5}{6}$$+2$$\frac{3}{8}$$; B) 4$$\frac{5}{14}$$+(5$$\frac{1}{12}$$-3$$\frac{4}{21}$$).

a) 3$$\frac{4}{7}$$-2$$\frac{3}{5}$$ = $$\frac{25}{7}$$ - $$\frac{13}{5}$$ = $$\frac{25 \cdot 5 - 13 \cdot 7}{35}$$ = $$\frac{125-91}{35}$$ = $$\frac{34}{35}$$

б) 6$$\frac{5}{6}$$+2$$\frac{3}{8}$$ = $$\frac{41}{6}$$ + $$\frac{19}{8}$$ = $$\frac{41 \cdot 4 + 19 \cdot 3}{24}$$ = $$\frac{164 + 57}{24}$$ = $$\frac{221}{24}$$ = 9$$\frac{5}{24}$$

в) 4$$\frac{5}{14}$$+(5$$\frac{1}{12}$$-3$$\frac{4}{21}$$) = $$\frac{61}{14}$$ + ($$\frac{61}{12}$$-$$\frac{67}{21}$$) = $$\frac{61}{14}$$ + $$\frac{61 \cdot 7 - 67 \cdot 4}{84}$$ = $$\frac{61}{14}$$ + $$\frac{427 - 268}{84}$$ = $$\frac{61}{14}$$ + $$\frac{159}{84}$$ = $$\frac{61 \cdot 6 + 159}{84}$$ = $$\frac{366 + 159}{84}$$ = $$\frac{525}{84}$$ = $$\frac{25}{4}$$ = 6$$\frac{1}{4}

Ответ: a) $$\frac{34}{35}$$; б) 9$$\frac{5}{24}$$; в) 6$$\frac{1}{4}$$