In January of 2005, the country of Greeze issued 10-year, 8% coupon bonds, with interest paid

 In January of 2005, the country of Greeze issued 10-year, 8% coupon bonds, with interest paid

annually on 12/31. The bonds sold at par on 1/1/2005. On 12/31/2005, Greeze paid the required interest, but then announced that they had no intention of paying the rest of what they owed. 

Greeze said that going forward, they would pay only 4% for the remaining 9 years. And at maturity, investors should only expect to receive $600, instead of the $1,000 par value. Bond investors worldwide accepted the offer (rather than declaring war). And all bond investors agree that an appropriate discount rate for the remaining cash flows was 15%. 

What is the resulting YTM for this bond?