Answer
$(i) : COOH^-$
$(ii) : {PO_4}^{3-}$
Work Step by Step
Write the equations where the $HCOOH$ and the ${HPO_4}^{2-}$ act like an acid:
$(i) : HCOOH + H_2O --> COOH^- + H_3O^+$
$(ii) : {HPO_4}^{2-} + H_2O --> {PO_4}^{3-} + {H_3O}^+$
The bases formed in these reactions are the conjugated bases.