Can you do 9b?

9. (a) You have been asked to determine the least expensive route for a telephone cable which connects Andersonville with Beantown, If it costs $5000 per mile to lay the cable on land and $8000 per mile to lay X the cable across the river and the cost of the cable is negligible, find the least expensive route rever (b) What is the least expensive route if the cable costs $7000 per mile plus the cost to lay it