lowest possible cost

[kcarl]

a local travel provider ferries tourists from the airport located on the shorew of the mainland to an island located 5 miles down shore and 3 miles out to the sea. transporting tourists on land costs .1 dollars/mile/person while travel across water costs .12 dollars/mile/person. determine how far tourists should be transported on land and sea so that the total cost of transportation is a minimum.

 

[stapel]

a local travel provider ferries tourists from the airport located on the shorew of the mainland to an island located 5 miles down shore and 3 miles out to the sea. transporting tourists on land costs .1 dollars/mile/person while travel across water costs .12 dollars/mile/person. determine how far tourists should be transported on land and sea so that the total cost of transportation is a minimum.

The standard solution method should be fairly simple to set up. (You'll be using cost as the parameter, rather than speed, of course.) Where are you stuck in the process?

Please be complete. Thank you!