Trey Monson starts a merchandising business on December 1 and enters into the following three inventory purchases. Also, on December 15, Monson sells 15 units for $20 each.

Purchases on December 7	10 units @ $ 6 cost
Purchases on December 14	20 units @ $12 cost
Purchases on December 21	15 units @ $14 cost

Required

Monson uses a perpetual inventory system. Determine the costs assigned to the December 31 ending inventory based on the FIFO, LIFO, and weighted average methods.