$!$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 $$30$ each.

Purchases on December $710$ units @ $$16\mathrm{.}00$ cost

Purchases on December $1420$ units @ $$22\mathrm{.}00$ cost

Purchases on December $2115$ units @ $$24\mathrm{.}00$ cost