72. The per-unit standards for direct materials are 2 gallons at $4 per gallon. Last month, 2,800 gallons of direct materials that actually cost $10,600 were used to produce 1,500 units of product. The direct materials quantity variance for last month was a. $800 favorable. b. $600 favorable. c. $800 unfavorable. d. $1,400 unfavorable.