Complete the Square? Parabola?

Alright, so I recently started my new semester, and I've forgotten almost everything that I've learned the previous year regarding math. I was assigned to do various questions, and I'm not exactly sure how to do it. The question is:

*Rebecca has 600 m of fencing for her cornfield. The creek that goes through her farmland will form one side of the rectangular boundary. Rebecca considers different widths to maximize the area enclosed.*

A. What are the minimum and maximum values of the width of the field?

I'm assuming that I will need to create a parabola for this question, due to the question asking a minimum and maximum. I also have the feeling completing the square will be involved, but I pretty much forgot how to do both. But here's what I got so far:

P = L + 2W *(the creek makes up 1 length?)*

L = 600 - 2W

A = W X L

That's all I got for now... any help, please?

B. What equations describe each?

i) The relationship between the length and width of the field.

ii) The relationship between the area and width of the field.

C. Copy and complete these table of values for widths that go from the least to greatest possible values in intervals of 50 m.

Width (m) | Length (m) | Area (m^2)