I need help figuring out the following question please. I'm completely lost.

Exercise:

Laker Co. reported the following January purchases and saled data for its only produce.

Units Accuired at Cost Units Sold at Retail
Beginning Balance ....140 units @ $6.00 = $840
Sales............................................. ..................................100 Units @ $15
Purchased ...............300 units @ $5.60 = $1680
Sales............................................. ..................................250 Units @ $15
Purchased................100 units @ $5.00 = $500

Totals......................540 units ..............$3020....................350 units


Laker uses a perpetual inventory system. Ending inventory consists of 190 units, 100 from the January 30 purchase, 70 from the January 20 purchase, and 20 from beginning inventory. Determine the cost assigned to ending inventory and to cost of goods sold using a) specific identification, b) weighted average, c) FIFO, and d) LIFO.


Could someone please explain to me how I figure these so that I can understand.

Thanks in advance.