You can
put this solution on YOUR website!You don't have any information explicity giving you l or w, but you can create a system of equations. Use the definition of the perimeter to give you one equation:

or:

The other equation requires you to use the ratio of length & width the problem gives you, that is that it is twice as long as it is wide or in math:

Substituting for w in the first equation with 2l from the second equation will allow you to solve it.