Đáp án:
Giải thích các bước giải:
$a)\dfrac{4}{7}.x-\dfrac{2}{3}=\dfrac{1}{5}$
$\dfrac{4}{7}.x=\dfrac{1}{5}+\dfrac{2}{3}$
$\dfrac{4}{7}.x=\dfrac{13}{15}$
$x=\dfrac{13}{15}:\dfrac{4}{7}$
$\to x=\dfrac{91}{60}$
$b)\dfrac{2}{9}-\dfrac{7}{8}x=\dfrac{1}{3}$
$\dfrac{7}{8}x=\dfrac{-1}{9}$
$x=\dfrac{-1}{9}:\dfrac{7}{8}$
$x=\dfrac{-8}{63}$
$c)\dfrac{4}{5}+\dfrac{5}{7}:x=\dfrac{1}{6}$
$\dfrac{5}{7}:x=\dfrac{-19}{30}$
$x=\dfrac{-150}{133}$