McKenna's Florida Division is currently purchasing a part from an outside supplier. The company's Alabama Division, which has excess capacity, makes and sells this part for external customers at a variable cost of $15 and a selling price of $27. If Alabama begins sales to Florida, it (1) will use the general transfer-pricing rule and (2) will be able to reduce variable cost on internal transfers by $4. If sales to outsiders will not be affected, Alabama would establish a transfer price of