I would like some one to explain the answers for the following question.

I would like some one to explain the answers for the following question. the answers are given but i want the explanation and the calculation how we got the answer

1-  A $25 000, 6% bond redeemable at par is purchased 11 years before maturity to yield 6.9% compounded semi-annually. If the bond interest is payable semi-annually, what is the purchase price of the bond? Is it premium or discount? Find the amount of it.   $23 285.32, Discount = $1714.68

2-

6) Karen Peters bought their neighbor's farm for $450 000.00 down and payments of $67100.00 at the end of every six months for 7 years. What is the purchase price of the farm if the semi-annual payments are deferred for four years and interest is 5.5% compounded semi-annually? $1 070 620.34

3-

 Calculate the amount of money that needs to be invested today at 4.8% compounded semi-annually to provide monthly payments of $500.00 in perpetuity starting one year from today. $12 0872.64 

4) Payments of $10 200.00 due one year ago and $13 000.00 due nine months ago are to be replaced by a payment of $5800.00 now, a second payment of $10 000.00 fifteen months from now, and a final payment twenty-four months from now. What is the size of the final payment if interest is 9.2% compounded quarterly? $12,431.49.