An island is 9 mi from the nearest point on a straight shoreline; that point is 12 mi from a power station (see figure). A Utility company plans to lay electrical cable underwater from the island to the shore and then underground along the shore to the power station. Assume that is costs $2600/mi to lay cable underwater and $1300/mi to lay underground cable. At what point should the underwater cable meet the shore to minimize the cost of the project? Island Cable 9 mi Power Station - 12 mi Write an equation for the total cost, C, as a function of x, where x is the distance from the shoreline closest to the island and the point where the cable leaves the shore. C= (Type an expression.) The interval of interest of the objective function is (Simplify your answer. Type your answer in interval notation.) The cost is minimized when x is. , mi. (Type an exact answer.) The minimum installation cost is $ (Round to the nearest cent as needed.)