If Pizana Computer Company manufactures the carrying cases, fixed factory overhead costs will not increase and variable factory overhead costs associated with the cases are expected to be $25\%$ of the direct labor costs.

a$.$ Prepare a differential analysis dated May $31$ to determine whether the company should make $($Alternative $1)$ or buy $($Alternative $2)$ the carrying case.

b$.$ On the basis of the data presented, would it be advisable to make the carrying cases or to continue buying them? Explain.