A gas cylinder containing 6.38 mol of neon has a pressure of 491 mm Hg at 295 K. If 3.22 mol of helium is added to this cylinder, at constant temperature and volume, what will be the pressure in the cylinder?

Use the ideal gas equation?

First find the number of moles of Ne in terms of volume V and ideal gas constant R.
Add this to the number of moles of He.
Then use the ideal gas equation again to get the pressure in mm Hg.