Periodic Inventory by Three Methods

The units of an item available for sale during the year were as follows:

Jan. $1$ Inventory $10$ units @ $$33$

Feb. $17$ Purchase $18$ units @ $$35$

July $21$ Purchase $20$ units @ $$37$

Nov. $23$ Purchase $11$ units @ $$39$

There are $10$ units of the item in the physical inventory at December $31.$ The periodic inventory system is used.