Last month the opening inventory was 6,000 units and the closing inventory was 4,000 units. Using absorption costing, this closing inventory was valued at $33,000. Using marginal costing last month's profit was $50,000 and using absorption costing it was $41,000. What was the variable production cost per unit last month? 0 $4.50 O $3.75 0 $6.00 0 $8.25