The officers of a high school senior class are planning to rent buses and vans for a class trip.Each bus can transport 36 students, requires 4 supervisors and costs Birr 1000 to rent

The officers of a high school senior class are planning to rent buses and vans for a class trip. Each bus can transport 36 students, requires 4 supervisors and costs Birr 1000 to rent. Each van can transport 6 students, requires 1 supervisor, and costs Birr150 to rent. The officers must plan to accommodate at least 420 students. Since only 48 parents have volunteered to serve as supervisors, the officers must plan to use at most 48 supervisors. How many vehicles of each type should the officers rent in order to minimize the transportation costs? What is the minimum transportation cost?