can you help me with the answer to this multiple-choice question?

Sheffield Bookstore had 470 units on hand at January 1, costing $8 each. Purchases and sales during the month of January were as follows:

Date		Purchases	Sales
Jan. 14			430 @ $13
17		250 @ $10
25		230 @ $12
29			200 @ $16

Sheffield does not maintain perpetual inventory records. According to a physical count, 320 units were on hand at January 31. The cost of the inventory at January 31, under the FIFO method is:

$2560.

$3660.

$3240.

$3370.