Date	Transaction	Quantity	Price/Cost
1/1	beginning inventory	2,000	$20
3/15	purchase	3,500	$25
4/1	sale	3,900	$45
6/15	purchase	1,700	$30
10/30	sale	2,200	$65

a) calculate "cost of goods sold" under a LIFO perpetual inventory system

b) calculate "cost of goods sold" under a FIFO periodic inventory system

c) calculate "cost of goods sold" under an average cost (moving average) perpetual inventory system