can someone help me + calculations

3. Franz is a manufacturer. Inventory is valued using the continuous weighted average method. At 1 August 2020 it held inventory of 2,400 units of product Z, valued at $10 each. During the year the following transactions in product Z took place: 14 November 2020 28 January 2021 7 May 2021 Sell Purchase Sell 900 units 1,200 units for $20,100 1,800 units What was the value of Franz's inventory of Zobdo at 31 July 2021? A $9,000 B $11,700 C $15,075 D $35,100