【求助】关于计算refinancing break even interest rate问题

tkuser

题目如下：
Bank has liabilities of $4 million with an average maturity of two years paying interest rates of 4.0 percent annually. It has assets of $5 million with an average maturity of 5 years earning interest rates of 6.0 percent annually.
What is the maximum interest rate that it can refinance its $ million liability and still break even on its net interest income in dollars?
A.         6.5 percent.

B.         7.0 percent.

C.         7.5 percent.

D.         8.0 percent.

E.         8.5 percent.

求老师解答写出计算步骤~~

cashking

这题没啥意思，选C.
let NII=5*6%-4*r=0
r=7.5%