The given equation cannot be balanced as it violates the law of conservation of mass. The reactants, ammonium phosphate and lead nitrate, contain different elements and cannot simply be rearranged to form only the product, nitrate. Balancing a chemical equation involves adjusting the coefficients in front of the reactants and products to ensure that the number of atoms of each element is equal on both sides of the equation. In this case, it is not possible to achieve this without introducing additional compounds.