Common Concentration (C)

The common concentration of a solution is the ratio between the mass of the solute in grams and the volume of the solution in liters.

C = common concentration (g / L)
m1 = mass of solute (g)
V = volume of solution (L)

What is the common concentration in g / l of a 3L solution with 60 g of NaCl?

Common concentration is different from density, although the formula is similar. See the difference:

The density is always the solution, so:

At the common concentration, only msolute, ie m1.