answer from the expert for balancing the following equation is not correct.

Mg3N2+H2O gives out Mg(OH)+NH4

I have searched for the mentioned question but could not able to find it. Please provide the link and mention the name of expert, only then we will be able to offer you a meaningful help. 
However, I would like to mention that the above reaction is incorrect. Mg₃N₂ on reaction with water yields magnesium hydroxide and ammonia gas instead of ammonium ions. 
Following is the chemical equation for the reaction:
​Mg₃N₂ + 6H₂O → 3Mg(OH)₂ + 2NH₃