high school accounting

Fv=PV x ($1+r/c)^N PV=FV x 1/($1+r/c)^n -1/r/C FV=ANN X ($1 + r/can PV=Ann x ($1-$1/($1+r/c)^n/r/c im using these to find the answer to the problem but I don't know which ones to use and solve 1. You are going to put $2,500 into a savings account every month starting Sept 1, 2009, with the last payment on March 1, 2011. How much will be in the savings account on March 1, 2011, if you can earn a 4% annual rate? 2. How much must you invest today to receive $3,000 per month for twenty months (starting month from today) if you can earn 6% annual interest? 3. You have just purchased a new Mercedes for $52,000. You have paid $5,000 down and have financed the rest. The financing arrangement calls for you to make monthly payments for the next 5 years at 7% interest. What will be the amount of your monthly payment? How much of the first payment goes to pay the principal of the note? 4. Your client is 25 years old and wants to have $1,000,000 when she retires on her 54th birthday. As her financial advisor, how much must she invest every year starting today (on her 25th birthday) to achieve her goal if she can earn 8 percent annual interest? (Her last payment will be on her 54th birthday