An underground telephone cable is to be laid btwn 2 boathourses on opposite banks of a straight river. One boathouse is 600 meters downstream from the other. The river is 200 meters wide. If the cost of laying cable is $150 per metere underwater and $80 per metere on land, how should the cable be laid to minimize cost? Can someone help me figure this out and show how they did it? Thank u so much if u can.