Please assist to understand calculations. Thank you

Flash Computers, a seller of computers, had an inventory of 40 computers at R7 700 each

on hand on 01 January 2016, the start of the financial year.

During 2016 the following purchases were made:

580 units at R8 400 each on 25 February 2016

200 units at R8 800 each on 30 September 2016

60 units at R9 000 each on 15 November 2016

During the year 780 computers were sold at R14 000 each.

Required:

1.1 The value of closing inventory and cost of sales if the FIFO method of valuing

inventories is used.

1.2 The value of closing inventory and gross profit if the weighted average cost method

of valuing inventories is used.

1.3 List five (5) factors that affect the demand of stock.