Units Produced Total Cost 1,600 1,300 1,500 1,100 $66,000 57,000 67,500 49,500 If the high-low method is used, what is the monthly total cost equatio a. Total cost $9,900 $36/unit b. Total cost $13,200 + $33/unit c. Total cost $16,500 $30/unit d. Total cost $0 $45/unit