Were can you find a protector on Pokemon Diamond?

a veterinarian uses 600 feet of chain-link fence to enclose a rectangular region. It is subdivided evenly into two smaller rectangles by placing fence parallel to one of the sides.

what is the width (w) as a function of the length (L)? (w=?)

what is the total area as a function of (L)? (A=?)

what are the dimensions that produce the greatest enclosed area?

EXPLENATION PLEASE