The concentration of Ca2+ in a particular water supply is 5.7 × 10-3. The concentration of bicarbonate ion, HCO3-, in the same water is 1.7 ×10-3. What masses of Ca(OH)2 and Na2CO3 must be added to 5.0 ×107L of this water to reduce the level of Ca2+ to 20% of its original level?