Consider the following table outlining the inventory movements for company XXX Ltd during the year to 31/12/2019: date transaction units unit price () 01/01/2019 opening inventory 400 5 14/01/2019 purchase 600 8 03/03/2019 sale 800 15 24/03/2019 purchase 200 10 12/05/2019 purchase 400 12 03/08/2019 sale 200 20 07/09/2019 sale 500 18 21/11/2019 purchase 300 12 a) Calculate cost of goods sold and closing inventory at 31/12/2019 using average cost. Show your calculations for each step. [15 marks]