June and Al have just sold their home and are planning to travel around the world for a few years before finding a place to settle down. They received $740,000 for their home and they currently have a $310,000 mortgage on the home with 3 years left in the term and an interest rate of 4%. The original mortgage amount when they purchased the home was $450,000.00. The current interest rate for a 3 year fixed rate mortgage is 6%. The couple has been told they will be subject to a three month interest penalty. How much will their penalty ?