Chapter 15, Problem 7PE

Given that ${\text{HSO}}_{\text{4}}{}^{\text{-}}$ is a stronger acid than ${\text{HPO}}_{\text{4}}{}^{{\text{2}}^{\text{-}}}\text{,}$ what is the chemical reaction if solutions containing these ions are mixed together? (Hint: One of these must act as an acid and the other as a base.)