Ideal gas law, What stands for P

[kougou]

the ideal gas law, PV=nRT, I have question about the parameter P.
Does P stands for the pressure exert by the gas or the atmospheric pressure?


Say helium gases are enclosed inside a balloon. Then it gives pressure, temperature, and volume data to use the gas law. Does the pressure refer to the pressure of helium or the atmospheric pressure?

 

[haruspex]

It's the pressure of the gas.