A company has been purchasing carrying cases for portable devices at a purchase price $59 per unit. Currently operating below full capacity, charges factory overhead to production at rate of 40% of direct labor costs. Fully absorbed unit costs to produce comparable products are expected to be as followed.

Direct material $35.00

Direct labor 18.00

Overhead (40% of direct labor) 7.20

Total cost per unit $60.20

If the company manufactures the comparable products fix overhead will not increase and variable overhead cost associated with the products are expected to be 15% of direct labor cost/

how do I make a differential analysis to determine whether the company should make (alternative 1) or buy (alternative 2)