A solution of a salt of a weak acid $\ce{HY}$ is added to a solution of another weak acid $\ce{HX}$. Based on the information given above, which of the following species is the strongest base?

Since $K_{eq}\gt 1$, the products are favored. This must mean that the reaction between the reactants goes closer to completion than the reverse reaction. This implies that $\ce{Y-}$ does a good job of drawing $\ce{H+}$ from the acid. The ability to draw protons corresponds to the Brønsted-Lowry definition of a base.