can you please show me how to do problems 15-7, 15-15, 15-17, 15-18 & 15-19? thank you

cost of 12 percent, what is the maximum monthly charge it should pay for the lockbox system? 15-6 Currently, it takes five days from the time custo mail payments until Shark Bait Rafts (SBR) de them. SBR would like to set up a lockbox colle tion system that would reduce this collection f by three days. If SBR receives an average of $2,500 in payments per day and its opportunity cost is 18 percent, how much should SBR be willing to pay each month for the lockbox system? Compute the DSO for Buckwell Corporation, which has the following aging schedule: 15-7 Average Days 23 43 63 Amount Outstanding Account Age 0-30 days 31-60 days Over 60 days $65,000 25,000 10,000 Following is the aging schedule for QRM Corporation: 15-8 Average Days Account Age 0-30 days 31-60 days Over 60 days Amount Outstanding $100,000 70,000 30.000 40