Pasture Land

A rancher has a prize bull and some cows on his ranch. He has a large area for pasture that includes a stream running along one edge. He must divide the pasture into two regions, one region large enough for the cows and the other, smaller region, to hold the bull.

The bull's pasture must be at least 1,000 square meters and the cow pasture must be at least 10,000 square meters to provide grazing. The basic shape of the pasture is a rectangle 120 meters by 150 meters. The river runs all the way along the 120-meter side.

Fencing costs $5/meter and each fence post costs $10. Any straight edge of fence requires a post every 20 meters, and any curved length of fence requires a post every 10 meters. Help this rancher minimize his total cost of fencing.