?Coram Audio makes wireless headphones. Each pair of headphones comes with a travel case. Since its founding, Coram has manufactured its own travel cases. Recently, Holmur Travel Gear $($HTG$),$ ?a local outfitter that manufactures and sells backpacks, tent cases, and so on$,$ ?contacted Coram and proposed that they produce the headphone travel cases. Based on management experience, Coram's cost per travel case is as follows $($based on annual production of $40,800$ ?units$).$

?

Direct materials $ $10\mathrm{.}00$

Direct labor $21\mathrm{.}20$

Variable overhead $6\mathrm{.}40$

Fixed overhead $4\mathrm{.}70$

Total $ $42\mathrm{.}30$

?

HTG has offered to sell the case to Coram for $$39$ ?each. The total order would amount to $40,800$ ?travel cases per year. Coram's management decides that they will make the switch to HTG cases if Coram can save at least $$12,400$ ?per year. Accepting the offer would eliminate annual fixed overhead of $$77,520.$

Required:

a$.$ ?Prepare a schedule that shows the total differential costs.

b$.$ ?Should Coram continue to make the travel cases or buy them from HTG$?$