To balance the equation for this reaction, we first need to write down the unbalanced equation:

Na2CO3 + NaHCO3 + Na2CO3 + BaCO3 -> ?

Next, we balance the equation by ensuring that the number of atoms of each element is the same on both sides of the equation. In this case, the balanced equation would be:

2 Na2CO3 + NaHCO3 + BaCO3 -> 2 NaCO3 + BaCO3

This balanced equation shows that 2 moles of Na2CO3, 1 mole of NaHCO3, and 1 mole of BaCO3 react to produce 2 moles of NaCO3 and 1 mole of BaCO3.