For the reaction: CO (g) + H2O (g) <=> CO2 (g) + H2 (g), an equilibrium mixture contains 0.500 moles each of carbon dioxide and hydrogen gas, and 0.200 moles each of carbon monoxide and water vapor in a 1.00 L container. How many moles of carbon dioxide would have to be added at constant temperature and volume to increase the amount of carbon monoxide to 0.300 moles?