How do I solve q22 and 23?

Question 22: A company is thinking of buying in an assembly that it currently makes. The cost of buying it in would be f13. The unit costs of making the assembly are Material $3, Labour $6, Variable Overhead 2, Depreciation of equipment f2, Apportioned overheads fl. The equipment used has no scrap value. Calculate the differential benefit/ (cost) of buying the assembly in. a. Nil b. El C. 12 d. $4 Question 23: Same information as Q22 but if the assembly is bought in equipment could be used for making another product with a contribution of f4 per unit. Calculate the differential benefit/ (cost) of buying the assembly in. a. Answer same as Q21 b. 16 C. E8 d. ((2)