auditing plz help asap

Dick is auditing the financial statements of a trading company with a significant amount of trade accounts receivable. He is satisfied that the accounts are correctly summarized and classified and that valuations are made in accordance with GAAP. Dick is planning to use accounts receivable confirmation requests to obtain sufficient appropriate evidence as to trade accounts receivable. + Required:+ a. Identify and briefly explain the two primary forms of accounts receivable confirmation requests. (3 marks) b. Assume that Dick has received a satisfactory response to the confirmation requests. Suggest any TWO methods on how Dick can evaluate collectibility of the trade accounts receivable. (2 marks)