\(2,\\ a,\Leftrightarrow-5x=\dfrac{1}{4}\Leftrightarrow x=-\dfrac{1}{20}\\ b,\Leftrightarrow\left|x-\dfrac{1}{4}\right|=\dfrac{7}{3}\\ \Leftrightarrow\left[{}\begin{matrix}x-\dfrac{1}{4}=\dfrac{7}{3}\\\dfrac{1}{4}-x=\dfrac{7}{3}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{31}{12}\\x=-\dfrac{25}{12}\end{matrix}\right.\)