A solvent is a liquid that dissolves a solid, liquid or gaseous solute. A solute is a substance dissolved in another substance. A solute and a solvent make up a solution.
the mass of the solution = mass of solvent (water) + mass of solute (NaCl)
the mass of the solution = 217 grams + 17.8 grams = 234.8 grams
Note:
according to the solubility of sodium chloride which given in the question 360 g/dm3 all the amount of NaCl added to water was totally dissolved.