CO2 +H2 = H2O + CO

is at equilibrium at some temperature. At equilibrium, a 4 L vessel contains 1 mole CO2, 1 mole H2, 2.4 moles H2O, and 2.4 moles CO. How many moles of CO2 must be added to the system to bring the equilibrium CO concentration to 0.768 mol/L