There are two closed vessels, one of H of 1.2L at 3atm and the other was of 2.8L of He at 9atm. If the vessels are connected, then what would be the pressure?

There are two closed vessels, one of H of 1.2L at 3atm and the other was of 2.8L of He at 9atm. If the vessels are connected, then what would be the pressure?