A farmer wants to fence a rectangular plot of land adjacent to the north bank of a river. no fencing is needed along the river, and the fencing along the west side of the fenced region will be shared with a neighbor who will pay for half of that portion of the fence. if the fencing costs $30 per linear foot to install and the farmer wants to enclose 4500 square feet of land, find the minimum cost of the fence (for the farmer).