a,
$\dfrac{1}{3}x-\dfrac{2}{5}x-\dfrac{2}{5}=0$
$\Leftrightarrow \dfrac{-1}{15}x=\dfrac{2}{5}$
$\Leftrightarrow x=\dfrac{2}{5}:\dfrac{-1}{15}=-6$
b,
$\dfrac{3}{4}+\dfrac{1}{4}x=\dfrac{1}{2}+\dfrac{1}{2}x$
$\Leftrightarrow \dfrac{3}{4}-\dfrac{1}{2}=\dfrac{1}{2}x-\dfrac{1}{4}x$
$\Leftrightarrow \dfrac{1}{4}x=\dfrac{1}{4}$
$\Leftrightarrow x=1$
c,
$\dfrac{11}{4}x=\dfrac{22}{7}:\dfrac{1}{100}$
$\Leftrightarrow \dfrac{11}{4}x=\dfrac{22}{7}.100=\dfrac{2200}{7}$
$\Leftrightarrow x=\dfrac{2200}{7}:\dfrac{11}{4}=\dfrac{800}{7}$
d,
$(5x-1)\Big(2x-\dfrac{1}{3}\Big)=0$
$\Leftrightarrow 5x-1=0\Leftrightarrow x=\dfrac{1}{5}$
Hoặc $2x-\dfrac{1}{3}=0\Leftrightarrow x=\dfrac{1}{6}$
