2.209 Вычислите: a) $$\frac{1}{6}-(1-\frac{17}{18})$$; б) $$3-(\frac{11}{14}-\frac{13}{21})$$; в) $$7\frac{14}{25}-(3\frac{8}{15}+1\frac{9}{10})$$; г) $$6\frac{3}{16}-2\frac{5}{24}-3\frac{11}{12}$$.

Выполним вычисления: а) $$\frac{1}{6}-(1-\frac{17}{18})$$ $$\frac{1}{6}-(1-\frac{17}{18})=\frac{1}{6}-\frac{1}{18}=\frac{3-1}{18}=\frac{2}{18}=\frac{1}{9}$$ б) $$3-(\frac{11}{14}-\frac{13}{21})$$ $$3-(\frac{11}{14}-\frac{13}{21})=3-(\frac{33-26}{42})=3-\frac{7}{42}=3-\frac{1}{6}=\frac{18-1}{6}=\frac{17}{6}=2\frac{5}{6}$$ в) $$7\frac{14}{25}-(3\frac{8}{15}+1\frac{9}{10})$$ $$7\frac{14}{25}-(3\frac{8}{15}+1\frac{9}{10})=7\frac{14}{25}-(3\frac{16}{30}+1\frac{27}{30})=7\frac{14}{25}-4\frac{43}{30}=7\frac{14}{25}-5\frac{13}{30}=7\frac{84}{150}-5\frac{65}{150}=2\frac{19}{150}$$ г) $$6\frac{3}{16}-2\frac{5}{24}-3\frac{11}{12}$$ $$6\frac{3}{16}-2\frac{5}{24}-3\frac{11}{12}=6\frac{9}{48}-2\frac{10}{48}-3\frac{44}{48}=6\frac{9}{48}-5\frac{54}{48}=5\frac{57}{48}-5\frac{54}{48}=\frac{3}{48}=\frac{1}{16}$$ Ответ: a) $$\frac{1}{9}$$ б) $$2\frac{5}{6}$$ в) $$2\frac{19}{150}$$ г) $$\frac{1}{16}$$