1. The problem statement, all variables and given/known data A drilling rig 12 miles off shore is to be connected by a pipe to a refinery onshore, 20 miles down the coast from the rig. If underwater pipe costs $40,000 per mile and land based pipe costs $30,000 per mile what value of x and y would give the least expensive connection? 3. The attempt at a solution I have no idea on where to start. I know I need to find a relevant equation, differentiate it, then set it to 0, and finally show that it is a relative minimum, but I'm having trouble finding the relevant equation. I recreated the image that was in my textbook, and attached it to this post. Thanks for your time.