Please show your work. If you used a calculator with PMT or PV buttons, then just put that next to the amount you put in. I am also working on these but am struggling. Please show your work so i can understand how to do it on my own.

A family wants to save money for a down payment on a summer cottage. If they can invest money at 5% compounded semiannually, how much must they invest each semiannual period, beginning in 6 months, to accumulate $15,000 in 8 years?