A TV company wants to put a cable from point Q to point P as shown in the diagram below. Point P is directly opposite point R and they are 100 m apart. Point R is 1200 m away from point Q on a direct line with point Q. It costs $400/m to lay cable on land and $800/m to lay cable under the river. Determine the cheapest method to lay the cable. Land R 1200 m River 100 m Land p