I have the question "A Gas Outlet is one one side of a river 120 m wide. It is exactly 300 meters downstream and across the river from a cottage. A gas line is to be constructed to join the outlet to the cottage. Underwater, the cost is 13 dollars per meter while on land it is 5 dollars per meter. Determine the length of a line that should be laid on land to minimize the cost of the construction of the pipeline".
I am unsure about how to solve this, I have looked at similar questions and could not find a solution to how I would solve this.