For the reaction 4HCl(g) + O2(g) ⇌ 2Cl2(g) + 2H2O(g), how many moles of gas are present at equilibrium?

Additional Information: 4 moles of HCl and 1 mole of O2 producing 2 moles of Cl2 and 2 moles of H2O gives a total of 6 moles of gas.