Hi, I don't understand how to get the answer for this?

Use the following information to answer questions (Round to 2 decimal places):

The following information has been extracted from the records of Due North Sales (DNS) Co.:

January 1	Beginning Inventory	550 units @ $26 each
January 9	Bought	1,000 units @ $28 each
January 15	Sold	1,200 units @ $40 each
January 25	Bought	750 units @ $30 each

If Due North Sales (DNS) uses the Weighted Average cost flow assumption, under a perpetual method, the ending inventory value at January 31st is (Round to 2 decimal places):

None of the other alternatives are correct$32,300$32,054$31,600$30,987