A chemical question: ionic equation?

I have an unknown Ba(x)Cl(y)*zH20 where x,y,z are unknown dissolved in water. I put sodium phosphate in order to get Ba3(PO4)2 solution. Now I am asked to determine the ionic equation of the precipitate. I have no clue as I do not know what is the real formulas of Ba(x)Cl(y)*zH20