Gelb Company currently makes a key part for its main product. Making this part incurs per unit variable costs of $1.70 for direct materials and $1.25 for direct labor. Incremental overhead to make this part is $1.60 per unit. The company can buy the part for $4. per unit. (a) Prepare a make or buy analysis of costs for this part. (Enter your answers rounded to 2 decimal places.) (b) Should Gelb make or buy the part