\(\dfrac{1}{7}+\dfrac{6}{7}:\dfrac{x}{2}=4\Leftrightarrow\dfrac{1}{7}+\dfrac{6}{7}.\dfrac{2}{x}=4\Leftrightarrow\dfrac{1}{7}+\dfrac{12}{7x}=4\)
\(\Leftrightarrow\dfrac{12}{7x}=\dfrac{27}{7}\Leftrightarrow12.7=27.7x\Leftrightarrow84=189x\)
\(\Leftrightarrow x=\dfrac{84}{189}=\dfrac{4}{9}\) vậy \(x=\dfrac{4}{9}\)
