For speeds between 40 mph and 65 mph, a diesel truck gets 360/x miles per gallon when driven at a constant speed of x miles per hour. Diesel gasoline costs 4.9 dollars per gallon. The driver is paid 19 dollars per hour.

a) What is the total cost to have the truck driven 50 miles at a constant speed of 50 miles per hour?

b)What is the best constant speed to drive the truck to minimize the total cost to drive it 50 miles?

c)How much money is saved, per 50 miles, by driving at the the constant speed you found in problem B) instead of 50 miles per hour?