7. A 10 year bond with a coupon rate of 7.2% was issued 6 years ago. It has a $1,000 face value and pays a quarterly coupon. If the yield to maturity is 6.4%, set up a calculation to find the bond price. (Note you do not have to solve). (6 points).

solution=18/(1.016) + 18/(1.016^2) + ... + 1018/(1.016^16)

my question is why is "18" and "^16",how to compute the number 18? and why the number is ^16? plz explain it step by step. thank you so much!