\(\Leftrightarrow\left[{}\begin{matrix}\dfrac{3}{7}-2x=\dfrac{2}{3}\\\dfrac{3}{7}-2x=-\dfrac{2}{3}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}2x=-\dfrac{5}{21}\\2x=\dfrac{23}{21}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-\dfrac{5}{42}\\x=\dfrac{23}{42}\end{matrix}\right.\)