\(\dfrac{1}{3}:\left(2x-1\right)=-5-\dfrac{1}{4}\)
\(\dfrac{1}{3}:\left(2x-1\right)=\dfrac{-21}{4}\)
\(2x-1=\dfrac{1}{3}:\dfrac{-21}{4}\)
\(2x-1=\dfrac{-1}{21}\)
\(2x=\dfrac{-1}{21}+1\)
\(2x=\dfrac{20}{21}\)
\(x=\dfrac{20}{21}:2\)
\(x=\dfrac{10}{21}\)