(20 points) Robert California is an investor, who bought a 15-year bond with a face value of 100,000 and 8% nominal yearly coupon rate and semiannual coupons. The bond is callable at par on any coupon date beginning with the 20th coupon. Robert wants to make sure his yield rate (yearly, nominal, compounded semiannually) is at least 10%. What's the maximum price he should be willing to pay