The team of auditors that were assigned to audit Goodyear Limited Company has completed their fieldwork. The financial year for the company ended June 30, 2020. The draft financial statement showed assets totalling $55m and profit before tax was $15m. The audit files are currently being reviewed. Goodyear manufactures and sells all different sizes of tyres to its customers islandwide via various distribution channels.

(a) There are various methods an audit can use to obtain audit evidence. List and explain these methods of obtaining audit evidence.          

(b) Using your answer in (a), explain how this evidence can be used to test the purchase of raw materials and other expenses of the company.