Answer:
Net incremental cost of buying = $2.1 per unit
Explanation:
$/unit
Relevant variable cost of production
= 9.90 + 23.90 + (60%*15.90)= 43.34
External purchase price 45.44
Net incremental cost of buying 2.1
Note the only 60% of the overhead are relevant, the balance of 40% would still be incurred whether the the product is produced internally or purchased from outside
Net incremental cost of buying = $2.1 per unit