(b) Give clear explanations of the treatment accorded to the following items in calculating the sales tax payable by/refundable to Mr Miskeen in part (a):(i) The purchases of packing material from unregistered persons. (1 mark)(ii) The supply of goods to unregistered persons. (1 mark)(iii) The supply of goods to registered persons at a trade discount of 35%. (3 marks)