a) \(\Rightarrow\dfrac{3}{5}:x=-2\Rightarrow x=-\dfrac{3}{10}\)
b) \(\Rightarrow\left|x+\dfrac{1}{3}\right|=\dfrac{1}{2}\)
\(\Rightarrow\left[{}\begin{matrix}x+\dfrac{1}{3}=\dfrac{1}{2}\\x+\dfrac{1}{3}=-\dfrac{1}{2}\end{matrix}\right.\)\(\Rightarrow\left[{}\begin{matrix}x=\dfrac{1}{6}\\x=-\dfrac{5}{6}\end{matrix}\right.\)