Could you tell us what you've tried so far, or just where your difficulty is? I could do the problem, but I'm not sure that would help you.

Here's a thought. Start at "time zero" (you can think of "time zero" as a date on the calendar, maybe January 1, 2000 if that seems to help) with $30K. The interest is compounded semiannually. What happens after six months (half a year)?