Mass of solute (sodium chloride) = 36 g (Given)
Mass of solvent (water) = 100 g (Given)
Then, mass of solution = Mass of solute + Mass of solvent
= (36 + 100 )g
= 136 g
Therefore, concentration (mass by mass percentage) of the solution
\\( \\begin{array}{l}{=\\frac{\ ext { Mass of solute }}{\ ext { Mass of solvent }} \ imes 100 \\%} \\\\ {=\\frac{36}{136} \ imes 100 \\%} \\\\ {=26.47 \\%}\\end{array} \\)