A city wants to lay a new high-voltage line from the power station, located on an avenue (say Madison ave) that runs North-South, to the downtown area. Due to existing buildings, the power line must be underground in any region east of Madison Avenue, but it can be built above ground along Madison Avenue. The additional cost of burying the power line doubles the cost per mile of installing it. The downtown area is 5 miles north and 6 miles east of the station. What is the least expensive route for the new power line