b. Sound Inc. reported the following results from the sale of 24,000 radios:

Sales	$528,000
Variable manufacturing costs	288,000
Fixed manufacturing costs	120,000
Variable selling costs	52,800
Fixed administration costs	35,200

Rhythm Co. has offered to purchase 3,000 radios at $16 each. Sound estimates approximately 5,000 units could be made with the capacity currently available in the factory. The owner of Sound is in favor of accepting the order. She feels it would be profitable because no variable selling costs will be incurred. The plant manager is opposed because his full cost of production is $17. What would the change in profit be if the special order is accepted?

b.	Per unit	Total (3,000 units)
Incremental Revenue	$16	$48,000
Incremental Costs	12	36,000
Incremental Income	$4	$12,000

How did they get 12 for incremental costs?