Đáp án:
$a) x=\dfrac{18}{5}$
$b) x=\dfrac{371}{160}$
$c) x=-\dfrac{35}{12}$
$d) x=\dfrac{19}{96}$
Giải thích các bước giải:
$a) \left ( -\dfrac{8}{5}+x \right ):\dfrac{12}{13}=\dfrac{13}{6}\\\Leftrightarrow \left ( -\dfrac{8}{5}+x \right ).\dfrac{13}{12}=\dfrac{13}{6}\\\Leftrightarrow -\dfrac{26}{15}+\dfrac{13}{12}x=\dfrac{13}{6}\\\Leftrightarrow -104+65x=130\\\Leftrightarrow 65x=130+104\\\Leftrightarrow 65x=234\\\Leftrightarrow x=\dfrac{18}{5}\\b) \dfrac{-4}{7}x+\dfrac{7}{5}+\dfrac{1}{8}:\dfrac{-5}{3}=0\\\Leftrightarrow -\dfrac{4}{7}x+\dfrac{7}{5}-\dfrac{1}{8}.\dfrac{3}{5}=0\\\Leftrightarrow -\dfrac{4}{7}x+\dfrac{7}{5}-\dfrac{3}{40}=0\\\Leftrightarrow -\dfrac{4}{7}x+\dfrac{53}{40}=0\\\Leftrightarrow -160x+371=0\\\Leftrightarrow -160x=-371\\\Leftrightarrow x=\dfrac{371}{160}\\c) \dfrac{1}{3}x+\left ( \dfrac{2}{3}-\dfrac{4}{9} \right )=-\dfrac{3}{4}\\\Leftrightarrow \dfrac{1}{3}x+\dfrac{2}{9}=-\dfrac{3}{4}\\\Leftrightarrow 12x+8=-27\\\Leftrightarrow 12x=-27-8\\\Leftrightarrow 12x=-35\\\Leftrightarrow x=-\dfrac{35}{12}\\d) \left ( \dfrac{5}{6}-\dfrac{3}{4} \right ):\dfrac{-2x}{3}=\dfrac{-12}{19}\\\Leftrightarrow \dfrac{1}{12}:\dfrac{-2x}{3}=-\dfrac{12}{19}\\\Leftrightarrow -\dfrac{1}{12}.\dfrac{3}{2x}=-\dfrac{12}{19}\\\Leftrightarrow -\dfrac{1}{4}.\dfrac{1}{2x}=-\dfrac{12}{19}\\\Leftrightarrow -\dfrac{1}{8x}=-\dfrac{12}{19}\\\Leftrightarrow \dfrac{1}{8x}=\dfrac{12}{19}\\\Leftrightarrow 19=96x\\\Leftrightarrow x=\dfrac{19}{96}$
