Quel-age tu?
We would have to ask her that, wouldn't we?
For example, if you want to say, "they are 14 years old" you would say ils sont 14 ans. :D
Quel age as tu?
If the rules are taken literally, yes - it is against the rules to ask personal information.
Ask them.
you can tell someones nationality by their references usually americans look mixed. for example if someone is german and french they would look mixed german and french.
Ask them for it.
Quel âge a votre animal de compagnie - How old is your pet. Quel est l'âge de votre chien - How old is your dog. Quel est l'âge de votre chat - How old is your cat.
French will benifite someones personality by helping you get into a university to learn something and that something will maybe if you like it become your job.
Ask them, or search for them on Yahoo.
Ask them.
their birth certificate / ask them / ask their friends / ask their family