A farmer has 1500 feet of fencing in his barn. He wishes to enclose a rectangular pen. Subdivided into two regions by a section of fence down the middle, parallel to one side of the rectangle. Express the area enclosed by the pen as a function of its width x.

2 answers

So you have 2 long sections (x) and 3 short sections (y).
3x+2y = 1500
The area is A = xy = x(1500-3x)/2
or, 2x+3y = 1500
whichever way you define width