Two gases, nitric oxide (NO) and oxygen, are initially confined to two separate glass flasks, connected by a tap of negligible volume. Initially, there is 6L of NO at a pressure of 2 atm and 2L of O2 at 2atm. The tap is opened, allowing the gases to mix and react. Assume constant temperature and the reaction goes to completion, producing as much nitrogen dioxide (NO2) as possible according to the following equation. What is the total pressure, in atm, in the system after the reaction?