Chapter 4, Problem 80E

What is the concentration of NaCl in a solution if titration of 15.00 mL of the solution with 0.2503 M ${\text{AgNO}}_3$ requires 20.22 mL of the ${\text{AgNO}}_3$ solution to reach the end point?

${\text{AgNO}}_3\left(aq\right)+\text{NaCl}\left(aq\right)\to \text{AgCl}\left(s\right)+{\text{NaNO}}_3\left(aq\right)$