Please solve this question ASAP in fully details and explaination.

A resort on the bank of a river 200 m wide, needs to run a waterline across the river and 600 rn upstream. They will build the waterline straight across the river to some point P and then run the waterline along side the river for the remaining distance. If it costs $ 13 [m to build the pipeline underwater and $ 5 [m to lay the pipe on the shore, how far up river should the point P be to minimize the construction cost? (a) The point P should be upstream C] m