Optimizing the area of a rectangle A rectangular field is bounded on one side by a river and on the other three sides by a fence. Additional fencing is used to divide the field into three smaller rectangles, each of equal area. 1080 feet of fencing is required. I want to find the dimensions of the large rectangle that will maximize the area.  
I had the following equations and I was wondering if they are correct: 
I let $Y$ denote the length of the rectangle. Then $Y=3y$. If $x$ represents the width of the three smaller rectangles, then I get the following: 
$$ 4x+3y = 1080,~~~\text{Area} = 3xy.$$

@Gorg, you are on the right track.  You can either solve this problem using small y or large Y.  Your equations are set up correctly with small y, and the answer I get if you want to compare with what you get is $$x=135 \text{ and}\ y=180$$.  Good job :)
