Find the largest area ( include units )

Question

A javalina rancher wants to enclose a rectangular area and then divide it into four pens with fencing parallel to one side of the rectangle (see the figure below). There are 460 feet of fencing available to complete the job. What is the largest possible total area of the four pens?

Answer 1

2 lengths = 460 - 5 widths

1 length = 230- 2.5 width

Area = w(230 - 2.5w)

Area = -2.5w² + 230w

Max at -b/2a where b = 230 and a = -2.5

-230/-5 = 46

Area = -2.5(46)^2 + 230*46 = 5290 ft^2