$[$The following information applies to the questions displayed below.$]$

Trey Monson starts a merchandising business on December $1$ and enters into the following three inventory purchases. Monson uses a perpetual inventory system. Also, on December $15,$ Monson sells $15$ units for $$27$ each.

Purchases on December $7$

Purchases on December $1A$

Purchases on December $21$

$10$ units e $$13\mathrm{.}00$ cost

$20$ units $$19\mathrm{.}00$ cost

$15$ units $$21\mathrm{.}00$ cost

Required:

Determine the costs assigned to the December $31$ ending inventory based on the FIFO method.