The Solubility of baking soda in water at room temperature is 9.30 g/100 ml. What is the concentration of baking soda in a saturated solution at room temperature?
The solubility is the maximum amount of a substance that will dissolve at a given temperature. A saturated solution contains that maximum amount that can be dissolved, so the solubility of 9.30 g/100 ml also describes the concentration of a saturated solution of baking soda at room temperature.
There are several units that can be used to express concentration. Percent by mass if often used. In this case the percent by mass of baking soda is the mass of the baking soda divided by the total mass, or 9.30 g/109.3 g = 8.5%. 100 ml of water is roughly 100 g at room temperature.
In chemistry it's customary to express concentration in molarity, which is moles of solute divided by liters of solution. There's not enough information given to calculate the total volume of the solution. If you assume that the 9.3 g of baking soda (sodium hydrogen carbonate) dissolves in 100 ml of water without a change in volume of the water, then you can calculate moles of sodium hydrogen carbonate and find the molarity as follows:
9.3g NaHCO3/84 g/mol = 0.11 mol NaHCO3
0.11 mol/0.100L = 1.1 moles/liter