To identify the mass of the solute, subtract the total mass by the mass of the graduated cylinder.
Thus, we have the following:
[tex]20.6g-2.55g=18.05g[/tex]
To obtain the concentration of the solution, divide the obtained mass by the total volume and then simplify.
Thus, we have the following:
[tex]\frac{18.05g}{74.79mL}=\frac{1805g}{7479mL}\approx0.241g\cdot mL^{-1}[/tex]
