Answer
the width is 6 in and the length is 18 in.
Work Step by Step
Let the width of the rectangle be $x$ and its length be $6+2x$. Now, since the perimeter of the rectangle is 48 in, then we have
$perimiter=2*length+2*width=48$
$$2x+2(6+2x)=48\Longrightarrow 6x=36\Longrightarrow x=6.$$
So, the width is 6 in and the length is 18 in.
