calculus question 2?

Question

Consider a rectangular industrial warehouse separated into 3 rectangular spaces of equal size. Assume that the wall materials cost 200$ per linear foot and the company allocates $2400,000 for the project. Find the area of each compartment if the total are of the warehouse is a maximum. Anyhelp is appreciated!

Answer 1

Total area will be max if floor is a square.
Thus walls will be (x+x/3)2 = 8x/3 linear feet
Hence 3*8x/3 = 8x = total linear feet
So 8x(200) = 2400000 --> x = 150 linear feet
Each compartment will have (150 +50)2 = 300 linear feet