Calculating Partial Pressures: Proving Dalton's Law

[theonlypirate]

I think this question is asking me to prove Dalton's Law, but I missed that day in class so I'm a little lost. Help?

Two bulbs of volumes VA and VB are connected by a stopcock. The number of moles of gases in the bulbs are nA and nB, and initially the gases are at the same pressure, P, and temperature, T. Show that the final pressure of the system, after the stopcock has been opened, is equal to P. Assume ideal-gas behavior.

 

[Ygggdrasil]

Try using the ideal gas law to find the final pressure of the system.