In the reaction 2SO2(g) + O2(g) ⇌2SO3(g), 2 moles of SO2 ,1 mole of O2 and 2 moles of SO3 are present in equilibrium. what is the number of moles of O2 be introduced into the vessel to increase the equilibrium moles of SO3 to 3 moles

Following is the given equilibrium,The volume of the container is not given let us assume it to be 1 litLet the moles of O2 to be introduced so that the moles of SO3 becomes 3 at equilibrium be x.Again,                    Now, 2 +2 y = 3 ⇒ y = 12   and at same temperature KC remains constant, equating both Kc  values