Answer
$$HCl(aq) + KHCO_3(aq) \longrightarrow CO_3(g) + H_2O(l) + KCl(aq)$$
Work Step by Step
1. This reaction has a carbonate and an acid as its reactants. Thus, it will produce $CO_3(g)$, $H_2O(l)$ and a salt made of the other ions:
$$HCl(aq) + KHCO_3(aq) \longrightarrow CO_2(g) + H_2O(l) + Salt$$
The remaining ions are: $K^{+}$ and $Cl^-$, therefore, the salt is $KCl$:
$$HCl(aq) + KHCO_3(aq) \longrightarrow CO_2(g) + H_2O(l) + KCl(aq)$$
2. Now, balance the equation.
The equation is already balanced.
