ABC company produces 2,000 office equipment annually for its main product. The costs per equipment are as follows: f6 tion Direct material 3 Direct labor 7 Variable overhead 4 Fixed overhead 7 Total They received an offer to buy the 2,000 units for $18 per unit. And, $4 of the fixed overhead per unit is unavoidable. How much is the differential cost of buying and producing? (write down your answer in number, eg: 60,000, or-60,000 if negative