When you posted this yesterday:
I'm trying to figure out the right data type and then declare each of them into variables[
^] you were given answers - so what is stopping you from doing it now?
And don't store "year of birth" and "age" - store "date of birth" and calculate "age" from that. "Age" isn't a fixed value-added it changes according to when you ask the question. For example, it may be illegal for someone to drink alcohol today, but tomorrow is third birthday so they reach the legal age and can drink without being arrested.