A homeowner took out a 20-year fixed-rate mortgage of $75,000. The mortgage was taken out 12 years ago at a rate of 7.5 percent. If the homeowner refinances, the charges will be $1,550. What is the highest interest rate at which it would be beneficial to refinance the mortgage? Note: Do not round intermediate calculations. Enter your answer as a percent rounded to 2 decimal places. Answer is complete but not entirely correct