Rain-Gutter Design:

An open rectangular gutter is made by turning up the sides of a piece of metal 20 in. wide. The area of the cross-section of the gutter is 50 in^2. Find the depth of the gutter.

So far this is what I have done:

A= LW

50 = L (20)

L = A/W = 50/20 = 2.5 in

Is this correct?