Let l be the length of the rectangle and w be its width.
Since the length of the rectangle is 1.5 times its width, then:
[tex]l=1.5w[/tex]The perimeter of the rectangle is given by the expression:
[tex]2(l+w)[/tex]Since the perimeter of the rectangle is four more than 3 times its length, then:
[tex]2(l+w)=4+3l[/tex]Substitute l=1.5w into that equation and solve for w:
[tex]\begin{gathered} \Rightarrow2(1.5w+w)=4+3(1.5w) \\ \Rightarrow2(2.5w)=4+4.5w \\ \Rightarrow5w=4+4.5w \\ \Rightarrow5w-4.5w=4 \\ \Rightarrow0.5w=4 \\ \Rightarrow w=\frac{4}{0.5} \\ \Rightarrow w=8 \end{gathered}[/tex]Substitute back w=8 into the expression for l to find its value:
[tex]l=1.5(8)=12[/tex]Therefore, the dimensions of the rectangle are:
[tex]8\times12[/tex]