Your solution will have a mass percent of 10.6%.
You're dealing with a percent concentration by mass solution, so you need to focus on two things
- the mass of the solute, in your case sodium chloride;
- the total mass of the solution.
Since you know what the target solution's density will be, you can use its volume to determine its total mass
You also know that the mass of the solute is equal to 98.6 g. Now all you have to do is figure out what percentage the mass of the solute holds in the total mass of the solution