a) $\dfrac{1}{2}-\dfrac{2}{3}x=\dfrac{7}{12}$
$\dfrac{2}{3}x=\dfrac{1}{2}-\dfrac{7}{12}$
$\dfrac{2}{3}x=\dfrac{-1}{12}$
$x=\dfrac{-1}{12}:\dfrac{2}{3}$
$x=\dfrac{-1}{8}$
Vậy $x=\dfrac{-1}{8}$
b) $\dfrac{3}{4}x+\dfrac{1}{5}=\dfrac{1}{6}$
$\dfrac{3}{4}x=\dfrac{1}{6}-\dfrac{1}{5}$
$\dfrac{3}{4}x=\dfrac{-1}{30}$
$x=\dfrac{-1}{30}:\dfrac{3}{4}$
$x=\dfrac{-2}{45}$
Vậy $x=\dfrac{-2}{45}$
c) $\dfrac{1}{6}x-\dfrac{3}{8}=\dfrac{1}{4}$
$\dfrac{1}{6}x=\dfrac{1}{4}+\dfrac{3}{8}$
$\dfrac{1}{6}x=\dfrac{5}{8}$
$x=\dfrac{5}{8}:\dfrac{1}{6}$
$x=\dfrac{15}{4}$
Vậy $x=\dfrac{15}{4}$
