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:
The perimeter of the rectangle is given by the expression:
Since the perimeter of the rectangle is four more than 3 times its length, then:
Substitute l=1.5w into that equation and solve for w:
Substitute back w=8 into the expression for l to find its value:
Therefore, the dimensions of the rectangle are: