A company began January with $9,000$ units of its principal product. The cost of each unit is $$5.$ Inventory transactions for the month of January are as follows:

$\backslash$table$[[$Date of Purchase,Unj,$\backslash$table$[[$Purchases$],[$Unit Cost$*]],$Total Cost$],[\backslash$table$[[$January $10],[$January $18]],\backslash$table$[[\backslash$table$[[6,000],[9,000]]]],\backslash$table$[[\backslash$table$[[$$$6$