Question

Farmer Jacky has $80,000 to spend on fencing. Her land has a river on the north border, so no fencing is required there. Due to the harsh east and west winds, she must use stronger, more expensive fencing on the east and west sides. Fencing costs $20 per foot on the east and west sides and $10 per foot on the south side (no fencing is required on the north side due to the river). How many feet of fencing must she buy to maximize the enclosed area?

Answer 1