To answer this question you will think of the length and the width as the following:
Length- 1.25w
Width-w
Using this you can then substitute in the information in your formula for finding the area of a rectangle.
A = lw
320 = 1.25w(w)
320 = 1.25 w^2; divide both sides by 1.25
256 = w^2; find the square root of both sides
w = 16 in
l = 1.25 x 16
l = 20 inches
The dimensions are a width of 16 inches and a length of 20 inches.
