XYZ Co$.$ produces all the parts it uses to manufacture its products. The following costs per unit were incurred in manufacturing $75,000$ units of Part B$99$:

Direct materials $$3\mathrm{.}50$

Direct labour $2\mathrm{.}00$

Variable overhead $1\mathrm{.}50$

Fixed overhead $6\mathrm{.}00$

A supplier has offered to sell $75,000$ units of part B$99$ to XYZ Co$.$ for $$12$ per unit. If XYZ Co$.$ accepts the offer, fixed overhead could be reduced by $50\%$ per unit. In addition, the facilities used to produce B$99$ could be used to manufacture Part C$182$ for which XYZ Co$.$ has been unable to meet current demand. Sales of C$182$ should increase by $30\%.$ The most recent income statement for part C$182$ is as follows:

Sales $$360,000$

Variable costs $168,000$

Fixed costs $120,000$

Operating income $72,000$

Required:

a$.$ Calculate the change in XYZ Co$.\text{'}$s incremental income if the supplier's offer is accepted.

b$.$ Should the supplier's offer be accepted?

c$.$ What qualitative factors should be considered?