a: =>|x-4|=3-2x
\(\Leftrightarrow\left\{{}\begin{matrix}x< =\dfrac{3}{2}\\\left(3-2x-x+4\right)\left(3-2x+x-4\right)=0\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x< =\dfrac{3}{2}\\\left(-3x+7\right)\left(-x-1\right)=0\end{matrix}\right.\Leftrightarrow x=-1\)
b: =>x-1=-3
=>x=-2