Gelb Co. currently makes a key part for its main product. Making this part incurs per unit variable costs of $1.20 for direct materials and $0.75 for direct labor. Incremental overhead to make this part is $1.40 per unit. The company can buy the part for $3.50 per unit. 

(a) Prepare a make or buy analysis of costs for this part.

(b) Should Gelb make or buy the part?