TOPIC: Change fee based on date of birth field (age) - how to?

What would be the best method to change the registration fee based on the date of birth field (age)? For example, there is a registration event that costs $100 and we wish to give juniors (younger than 18) a 50% discount, so they are charged only $50. And, seniors (60 and older) would receive a 30% discount. What would be the best method to do this and can it be done based on the date of birth field? (I know we can set up some check box fields to accomplish this but it would be handy if it could be done based on the date of birth.)
Thank you!

You can only apply fee changes to selection fields... and while a birthdate field has "selections", it's not the same. You do not control the values.

The best route would be to create an age dropdown field where they select their age. Then you can apply fee/discount options to each value (age) in that field. You can still have a separate birthdate field if you need that data, but a simple age selection will be needed to control the pricing based on that.

I do this with a drop-down box with two options for the age field: Younger than 18 yrs and Older than 18 yrs. I don't need any more granularity than that.