\(\Leftrightarrow\left[{}\begin{matrix}x+\dfrac{1}{3}=\dfrac{2}{7}\\x+\dfrac{1}{3}=-\dfrac{2}{7}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-\dfrac{1}{21}\\y=-\dfrac{13}{21}\end{matrix}\right.\)
\(\left|x+\dfrac{1}{3}\right|=\dfrac{2}{7}\\ \Rightarrow\left[{}\begin{matrix}x+\dfrac{1}{3}=\dfrac{2}{7}\\x+\dfrac{1}{3}=-\dfrac{2}{7}\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=-\dfrac{1}{21}\\x=-\dfrac{13}{21}\end{matrix}\right.\)
\(x-\dfrac{1}{3}=\dfrac{2}{7}\\ x=\dfrac{2}{7}+\dfrac{1}{3}\\ x=\dfrac{6}{21}+\dfrac{7}{21}=\dfrac{13}{21}\)
