The controller of ABC hospital would like to come up with a cost formula that links emergency department costs to the number of patients admitted during a month. The emergency department's costs and number of patients admitted during the past nine months follows: Month April May June July August September October November December Number of Patients Emergency Department Cost 18 19 17 15 15 11 11 48 16 P15,600 P15,200 P13,700 P14,600 P14,300 P13,200 P12,800 P72,500 P14,000 Required: Using the high-low method, determine: 1. The variable cost per unit 2. The annual fixed cost 3. The emergency department's monthly function 4. The department's estimated cost if 20 patients are expected to be admitted next month.