Consider a CMBS backed by a 80% loan to value loan of a $50,000,000 office building. The loan is interest only with 8% mortgage rate issued for 3 yrs with monthly payments. TheCMBS is issued with 37.5% subordination with a coupon rate on the senior tranche equal to 5% and coupon rate on the junior tranche equal to 7%. An interest only residual carrying no principal will be issued as well.

Suppose that in month 15 the borrower defaults on the underlying loan. After foreclosure 60% of property value is recouped. How much does tranche B receive in month 15? Assume that all the interest was paid for the month of default.

Please show work and explain. Thanks!