Fe2O3(s) + 3 CO(g) ⇌2 Fe(l) + 3 CO2(g)
According to Le Chatelier's principle change in concentration by changing the amount of reactant or product affect the equilibrium. However, the addition of solid reactant won't affect the concentration. Therefore, addition of solid Fe2O3 will not disturb the equilibrium. Same for Fe(l). Adding CO disturbs the equilibrium to the right, CO2 - to the left. Removing CO - left, removing CO2 - right.