X Company currently buys a part from a supplier for $13.16 per unit but is considering making the part itself next year. Estimated costs to make the part next year are:

		Per-Unit	Total
Direct materials		$2.56	$8,704
Direct labor		3.97	13,498
Variable overhead		3.90	13,260
Fixed overhead		5.10	17,340
Total		$15.53	$52,802

Of the estimated fixed overhead, $8,670 would be additional fixed overhead costs; the remainder would be common costs allocated to the part. X Company currently receives $2,500 a year by renting out unused factory space, but it will have to use this space to make the part.

This year, they purchased 3,400 units of this part, but they're not certain how many units they will need next year.

Q) How many units will make them indifferent between continuing to buy the part and making it?