For example, Michael owes $100,000 at 12% interest on a loan with 15 years left, borrowed 10 years ago. Current interest rates for 15-year loans are 6%. Arthur can refinance and reduce his payment from $1,200 per month to $844 per month.
用等额本息法算，是1200.1681 后边的算出来843.8568 。。我不知道跟题目有什么关系。。
顺便告诉你答案： Refinance means replacing an older loan with a new loan offering better terms.