This is not a balanced chemical equation. To balance it, we need to first determine the correct chemical formula for the products formed in the reaction between magnesium nitrate $Mg(NO3)2$ and phosphoric acid $H3PO4$. The correct balanced chemical equation for the reaction should be:

3Mg$NO3$2 + 2H3PO4 -> Mg3$PO4$2 + 6HNO3

This balanced equation shows that 3 moles of magnesium nitrate react with 2 moles of phosphoric acid to produce 1 mole of magnesium phosphate and 6 moles of nitric acid.