Explanation:
So this is the way I would look at this like, you could say that since it doubles by x2 every 12 years by 24 years it would or could be 200,00 since you have doubled once already from 50,000 to 100,000 on the 12 years your gonna multiple that by 2 as well since you have reached your year mark.
that's personally the way I would look at it but I'm sure other people will ne able to help aswell or change mine.