Parts a and b please. thank you!

You have decided to take your daughter skiing in Utah. The best price you have been able to find for a roundtrip air ticket is $713. You notice that you have 20,000 frequent flier miles that are about to expire, but you need 25,000 miles to get her a free ticket. The airline offers to sell you 5,000 additional miles for $0.06 per mile. a. Suppose that if you don't use the miles for your daughter's ticket they will become worthless. What should you do? b. What additional information would your decision depend on if the miles were not expiring? Why? a. Suppose that if you don't use the miles for your daughter's ticket they will become worthless. What should you do? By purchasing the miles, you will $. (Select from the drop-down menu and round to the nearest dollar.)