please answer part c in detail with formula and explanation

PROBLEM 3 United Health Group has bonds outstanding that have four years remaining to maturity, a coupon interest rate of 9 percent paid annually, and a $1,000 par value. a. What is the yield to maturity on the issue if the current market price is $829? b. If the current market price is $1,104? c. Would you be willing to buy one of these bonds for $829 if you required a 12 percent rate of return on the issue? Explain your