A bank has two, 3-year commercial loans with a present value of $70 million. The first is a $30 miltion loan that requires a single payment of $37.8 million in 3 years, with no other payments until then. The second is for $40 million. It requires an annual interest payment of $3.6 million. The principal of $40 million is due in 3 years. 9. a. What is the duration of the bank's commercial loan portfolio? b. What will happen to the value of its portfolio if the general level of interest rates increased from 8% to 8.5%