A mixture of CaCO3 and CaO weighing 0.705 g was heated to produce gaseous CO2. After heating, the remaining solid weighed 0.474 g. Assuming all the CaCO3 broke down to CaO and CO2, calculate the mass percent of CaCO3 in the original mixture. Just to note: I have tried two different answers, 84.3% and 49.1% and they are both wrong. Help is greatly appreciated.