What do you mean 12?
Well...let me see how I can better clarify this.
Let's go to the 4th year of Highschool Math. That would be Advanced remedial Core General stuff for you:
If you were 11 years old right now, how old will you be next year?
Mike is 3 years old and John is 4 time older than that, how many years old is John?
I hope this helps.