To make an item inhouse, equipment costing

$250,000 must be purchased. It will have a life of 4 years, an annual cost of $80,000, and each unit will cost $40 to manufacture. Buying the item externally will cost $100 per unit. At i  15% per year, it is cheaper to make the item inhouse if the number per year needed is:

a. above 1047 units

b. above 2793 units

c. equal to 2793 units

d. below 2793 units