Marcus Homer , a college student, plans to sell CD players over the internet & by mail order during the semester to help pay his expenses. He buys the players for $28 & sells them for $52. If payment by cheque accompanies the mail order (estimated to be 30% of sales), he gives 10% discount. If customers include a credit card number for either internet or mail order (estimated 40% of sales), they receive 5% discount. The remaining collections are estimated as follows: