\(\left(1-3x\right)+\left(x-3\right)=\left(5x-1\right)-\left(5x+3\right)\)
\(\Rightarrow1-3x+x-3=5x-1-5x-3\)
\(\Rightarrow\left(1-3\right)-\left(3x-x\right)=\left(5x-5x\right)-\left(1+3\right)\)
\(\Rightarrow-2-2x=-4\)
\(\Rightarrow2x=-2+4\)
\(\Rightarrow2x=2\)
\(\Rightarrow x=1\)
Vậy \(x=1\)