Let us assume the width of the rectangle = x inches
Then
The length of the rectangle = 2x inches
The perimeter of the rectangle as given in the question = 48 inches
We already know
Perimeter of a rectangle = 2 (Length + Width)
48 = 2 (2x + x)
48 = 2 (3x)
48 = 6x
x = 48/6
= 8
So
The width of the rectangle = 8 inches
And
The length of the rectangle = 2x
= 2 * 8 inches
= 16 inches
from the above deduction, we can easily say that the length of the rectangle is 16 inches and the width of the rectangle is 8 inches.