Question

Please identify the net ionic equation for Na3PO4 +ZnSO4=Zn3(PO4)2+ Na2SO4

Answer 1

Look for the precipitate, gas, or weak electrolyte. In this case it's the zinc phosphate that is insoluble.
PO4^-3(aq) + Zn^+2(aq) ==>Zn3(PO4)2(s)

Here is a site that gives the solubility rules.
http://www.files.chem.vt.edu/RVGS/ACT/notes/solubility_rules.html