It is not mentioned what is the chemical equation that results in the formation of sodium chloride from sodium hydrogen carbonate. But the answer to your query can be provided without that.
In any chemical reaction, the number of atoms of each element, which make up the compounds taking part in the reaction, remain the same on both the sides of the chemical equation.
Here, the number of atoms of sodium in sodium hydrogen carbonate and that is sodium chloride are the same.
3.25 moles of sodium hydrogen carbonate contains 3.25 moles of sodium. When sodium hydrogen carbonate reacts with any compound and sodium chloride is formed as a result, the number of moles of sodium in the sodium chloride formed is also 3.25.
Therefore, the number of moles of sodium chloride formed is 3.25.