Giúp em với mọi người ơi^^

Đáp án:

 $a) (3-\dfrac{3}{4}+\dfrac{2}{3})-(2+\dfrac{4}{3}-\dfrac{3}{2})-(1-\dfrac{7}{3}-\dfrac{9}{2})$

$= (\dfrac{36}{12}-\dfrac{9}{12}+\dfrac{8}{12})-(\dfrac{12}{6}+\dfrac{8}{6}-\dfrac{9}{6})-(\dfrac{6}{6}-\dfrac{14}{6}-\dfrac{27}{6})$

$= \dfrac{35}{12}-\dfrac{11}{6}-(-\dfrac{35}{6})$

$= \dfrac{35}{12}+4$

$= \dfrac{35}{12}+\dfrac{48}{12}$

$= \dfrac{83}{12}$

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$b) \dfrac{-1}{3}-\dfrac{8}{35}+\dfrac{-2}{9}-\dfrac{1}{135}+\dfrac{4}{5}+\dfrac{-4}{9}+\dfrac{3}{7}$

$= (\dfrac{-1}{3}+\dfrac{-2}{9}+\dfrac{-4}{9})+(\dfrac{3}{7}-\dfrac{8}{35}+\dfrac{4}{5})-\dfrac{1}{135}$

$= (\dfrac{-1}{3}+\dfrac{-2}{3})+(\dfrac{15}{35}-\dfrac{8}{35}+\dfrac{28}{35})-\dfrac{1}{135}$

$= (-1)+1-\dfrac{1}{135}$

$= 0-\dfrac{1}{135}$

$= -\dfrac{1}{135}$

~~~~~~~~~~~~~~~~~~~~~~~

$c) \dfrac{0,75+0,6-\dfrac{3}{7}-\dfrac{3}{13}}{2,75+2,2-\dfrac{11}{7}-\dfrac{11}{13}}$

$= \dfrac{\dfrac{3}{4}+\dfrac{3}{5}-\dfrac{3}{7}-\dfrac{3}{13}}{\dfrac{11}{4}+\dfrac{11}{5}-\dfrac{11}{7}-\dfrac{11}{13}}$

$= \dfrac{3.(\dfrac{1}{4}+\dfrac{1}{5}-\dfrac{1}{7}-\dfrac{1}{13})}{11.(\dfrac{1}{4}+\dfrac{1}{5}-\dfrac{1}{7}-\dfrac{1}{13})}$

$=\dfrac{3}{11}$