Xia Co. currently buys a component part for $5 per unit Xia believes that making the part would require $2 25 per unit of direct matenals and $1.00 per unit of direct labor Xia allocates overhead using a predetermined overhead rate of 200% of direct labor cost Xia estimates an incremental overhead rate of $0.75 per unit to make the part 1-a. What are the relevant costs for Xia to make or buy the part