Question 98824
     

let :
  l= length of the rectangle
  w = width of rectangle 
  p = perimeter of rectangle = 72 


  we know that  perimeter = sum of all the sides 
                so, p = l+l+w+w =2(l+w)

                since length is twice the width,
                    l= 2w
                so, p = 2(2w +w)

                  so, 72 = 2( 3w)
                   so, 72/2 = 3w
                    so, 36 = 3w
                     so, 36/3 = w
                      so, 12 =w

                so l = 2*12 = 24

   thus the length of the rectangle is 24in, and the width is 12in.

check :

  p = 2(l+w)
   p = 2(12 +24)
   p = 2 * 36
   p = 72