Define cost of purchases.
Refers to the value of the cost of the purchased goods that is recorded in the inventory account.
Name and explain the method used for calculating cost of sales.
First-In-First-Out(FIFO) method is used when calculating cost of sales. It assumes that goods that are purchased first will be sold first.
Explain,with a relevant accounting principle, how inventory is valued.
Inventory is valued at the lower of cost or net realisable value.
This is in accordance to the prudence concept, which states that a business must report and adjust for losses that it is likely to incur so that income and assets are not overstated.