First, we need to know the chemical formula of the substances involved. It is as follows:
Potassium Hydroxide = KOH
Phosphoric acid = H3PO4
Potassium Phosphate = KH2PO4
Water = H2O
The balanced chemical reaction should be written as:
KOH + H3PO4 = KH2PO4 + H2O
Hope this answers the question.