a) 11/12 – (2/5 +x) =2/3 b) -x-3/4 = -8/11

Đáp án:

 $a) \dfrac{11}{12} – (\dfrac{2}{5} +x) = \dfrac{2}{3}$

$⇔ \dfrac{2}{5} – x = \dfrac{11}{12} – \dfrac{2}{3}$

$⇔\dfrac{2}{5} – x = \dfrac{1}{4}$

$⇔ x = \dfrac{2}{5} – \dfrac{1}{4}$

$⇔ x = \dfrac{3}{20}$

Vậy $x=\dfrac{3}{20}$

$b) -x -\dfrac{3}{4} = -\dfrac{8}{11}$

$⇔ – x = -\dfrac{8}{11} + \dfrac{3}{4}$

$⇔ -x = \dfrac{1}{44}$

$⇔ x= -\dfrac{1}{44}$

Vậy $x=-\dfrac{1}{44}$