Giải thích các bước giải:
$a)$ $x+\dfrac{1}{5}-\dfrac{3}{7}=\dfrac{6}{35}$
$x+\dfrac{7}{35}-\dfrac{15}{35}=\dfrac{6}{35}$
$x=\dfrac{6}{35}+\dfrac{15}{35}-\dfrac{7}{35}$
$x=\dfrac{14}{35}=\dfrac{2}{5}$
$\text{Vậy $x=\dfrac{2}{5}$}$
$b)x×3-\dfrac{x}{4}=33$
$⇔\dfrac{12×x}{4}-\dfrac{x}{4}=33$
$⇔\dfrac{11×x}{4}=\dfrac{132}{4}$
$⇔11×x=132$
$⇔x=132:11=12$
$\text{Vậy $x=12$}$
$c)x×4+\dfrac{x}{3}=39$
$⇔\dfrac{12×x}{3}+\dfrac{x}{3}=\dfrac{117}{3}$
$⇔\dfrac{13×x}{3}=\dfrac{117}{3}$
$⇔13×x=117$
$⇔x=117:13=9$
$\text{Vậy $x=9$}$
Học tốt!!!
