A clinic takes patient blood pressure either using an automatic machine or a manual machine. The automatic machine takes 10 minutes per patient while the manual machine takes 15 minutes per patient. Since the automatic machine frequently breaks, at least twice as many patients must have their blood pressure taken by the manual machine than the automatic machine. However, at least 20 patient can be processed by the automatic machine. If the clinic is open for 20000 minutes, maximize the number of patients whose blood pressure can be taken.