The balanced equation for the reaction between calcium carbonate and phosphoric acid is:

3CaCO3 + 2H3PO4 → Ca3(PO4)2 + 3H2O + 3CO2

In this reaction, three moles of calcium carbonate (CaCO3) react with two moles of phosphoric acid (H3PO4) to produce one mole of calcium phosphate (Ca3(PO4)2), three moles of water (H2O), and three moles of carbon dioxide (CO2).