A hospital can transport their patients either using a type II ambulance or hospital van. The hospital needs to transport 320 patients every day. A type II ambulance is mounted on a truck-style chassis and can move 20 patients every shift and costs the hospital (including gas and salary) $820. A hospital van can move 15 patients and costs the hospital $550 every shift. The hospital can have at most 60% of shifts be hospital vans due to union limitations of the type II ambulance drivers. How many of shift using each type of vehicle should be scheduled to minimize the total cost to the hospital?