the answer should be $12,000. how do you get there?

Goodstone Tire Corporation sells tires for $90 each. Per-unit costs associated with producing and selling the tires are: Direct materials $35; Direct labor $10; Factory overhead $20. The variable portion of the factory overhead is $8 per unit. A foreign company wants to purchase 1,000 tires for $65 each. Assuming that Goodstone has excess capacity