Question 926473
You are told the that a rectangle has a Length that is twice its Width.

Let Width = W
Then Length = 2W

Area of a rectangle = {{{Length * Width}}} = {{{2W * W}}} = {{{2W^2}}}
Perimeter of a rectangle = {{{2*Width  = 2*Length}}} = {{{2W + 2*2W}}} = {{{2W +4W}}} = {{{6W}}}

You are told the area is 128 square feet
{{{128 = 2W^2}}}
{{{64 = W^2}}}
{{{8 = W}}}

{{{Perimeter = 6W}}}

{{{Perimeter = 6*8}}}

{{{Perimeter = 48}}}