Whenever you're dealing with pv = nrt (ideal gas) questions, I find the first method is to list what you have and what you don't have.
From here, often you can work it out mathematically without even understanding the chemistry (although, this is not recommended).
Fill in these details for me:
p1 = ?
p2 = ?
T1 =
T2 = T2 (this is what you are trying to find)
V1 = ?
V2 = ?