At the emergency room of Providence General Hospital entering patients initially go through a registration process that takes 3 minutes on average. When his or her turn comes, the patient is seen by a doctor and is either given detailed instructions for further care of the injury or illness, written a prescription, or admitted to the hospital. Time with the doctor averages 8 minutes for those given a prescription, 12 minutes for those given detailed instructions, and 30 minutes for those admitted to the hospital. Historically about 10% of patients are admitted to the hospital, 20% are given detailed instructions, and the remainder receive prescriptions. On average about 70 patients per hour arrive at the emergency room. An average of 10 people are waiting to be registered at any time, and 40 are registered but waiting to see a doctor. Assuming that the average inflow rate is equal to the average outflow rate (the system is stable)

a. On average,how long does a patient spend in the ER?

b. On average,how many patients are being examined by doctors?

c. On average,how many patients are there in the ER?

please explain with calculation and plz avoid handwriting

Thank you