Chemistry
posted by ChemLover .
A 30.9 L cylinder containing C2H4F2 at a pressure of 114.0 torr is connected by a valve to 0.865 L cylinder containing C4H10 at 114.0 torr pressure. Calculate the partial pressure (atm) of C4H10 when the valve is opened.

i just need to know how to solve it i already know the answer

Use P1V1 = P2V2 for C4H10 and ignore the C2H4F2. You know P1, you're looking for P2, you know V1 = 0.865L and you know V2 (0.865L + 30.9L)

thankk you sooo much but what is
what is P2??? 
ohhhh waitt nevermind i got it:)