An investor obtained a fully amortizing mortgage five years ago for $105,000 at 12% for 30 years. Mortgage rates have dropped so that fully amortizing 25 year loan can be obtained at 10.5%. There is no prepayment penalty on the mortgage balance of the orignal loan , but 4 points will be charged on the new loan and other closing costs will be $3,000. all the payment are made monthly. Should the borrower refinec if he plans to own the property only for 4 more years?