28. At an activity level of 6,000 units, the cost for maintenance is $7,200; at 10,000 units, the cost for maintenance is $11,600. Using the high-low method, what is the cost formula for maintenance? A. S1.16 per unit B. $1.20 per unit C.$600 plus $1.10 per unit. D. 1,200 plus $1.10 per unit 29. Selected information about Buehler Corporation's operations at high and at low levels of activity follow: level of Activity Low High Number of Units Produced 25,000 30,000 Total manufacturing overhead costs $575,000 $680,000 Direct material cost per unit SS S5 Direct labour cost per unit $6 soby Using the high-low method, what is the total variable cost per unit of product? A. $11.05 B. $21.00 C. $32.00 D. $35.00