help with accounting question please?

Question

Tevin Trader starts a merchandising business on December 1 and enters into three inventory purchases:
Trader sells 15 units for $25 each on December 15. Eight of the sold units are from the December 7
purchase and seven are from the December 14 purchase. Trader uses a perpetual inventory system.
Determine the costs assigned to the December 31 ending inventory when costs are assigned based on
(a) FIFO, (b) LIFO, (c) weighted average, and (d ) specific identification.

Answer 1

Tevin Trader starts a merchandising business on December 1 and enters into three inventory purchases: (info left out, provided by Cheryl S)
Dec. 7th 10 units @ $6 cost
Dec. 14th 20 units @ $12 cost
Dec. 21st 15 units @ $14 cost

Ending inventory :
(a) FIFO $390
(b) LIFO $300
(c) weighted average $340
(d ) specific identification $378

Worksheet will be emailed to you

Answer 2

Need to know the purchase price for the items. How much did Trader spend on them on December 7, 14, third purchase? We know what he sold them for but what did they cost him? Without the cost, this question can not be answered.