Write total ionic equations and then remove the spectator ions to write the net ionic equations. The (aq) subscript denotes that each species is soluble and dissociates in water.
Conjugate acid/base pairs: \text{H}_2\text{PO}_4^-/ \text{HPO}_4^{2-}\text{ and H}_2\text{O/OH}^- \\ \text{b) }\sout{\text{K}}^+(\sout{aq})+\text{HSO}_4^-(aq)+\sout{\text{2 K}}^+(\sout{aq})+\text{CO}_3^{2-}(aq)\leftrightarrows \sout{\text{2 K}}^+(\sout{aq})\text{SO}_4^{2-}(aq)+\sout{\text{K}}^+(\sout{aq})+\text{HCO}_3^-(aq) \\ \begin{matrix}\text{Net: HSO}_4^-(aq)+&\text{CO}_3^{2-}(aq)\leftrightarrows & \text{SO}_4^{2-}(aq) &+& \text{HCO}_3^-(aq) \\ \text{acid}&\text{base}&\text{conjugate base} && \text{conjugate acid} \end{matrix}
Conjugate acid/base pairs: \text{HSO}_4^-/\text{SO}_4^{2-}\text{ and HCO}_3^-/\text{CO}_3^{2-}