Inventory

Please, also give an explanation to this question.

A company with an accounting date of 31 October carried out a physical check of inventory on 4
November 20X3, leading to an inventory value at cost at this date of $483,700.
Between 1 November 20X3 and 4 November 20X3 the following transactions took place:
1 Goods costing $38,400 were received from suppliers.
2 Goods that had cost $14,800 were sold for $20,000.
3 A customer returned, in good condition, some goods which had been sold to him in October for
$600 and which had cost $400.
4 The company returned goods that had cost $1,800 in October to the supplier, and received a
credit note for them.
What figure should appear in the company’s financial statements at 31 October 20X3 for closing
inventory, based on this information?
A $458,700
B $505,900
C $508,700
D $461,500