What's the relation between molarity and molality?
$W$ and $V_{\text{sol}}$ can be related via the density of solution. We have, mass of solution = mass of solute + mass of solvent.
Hence, 
$$ M_{\text{sol}} = W + M’ $$

Let us assume the density of the solution to be $\rho$. Since, density is equal to mass over volume, we have,
 $$ \rho=  \frac{M_{\text{sol}}}{V_{\text{sol}}} = \frac{W + M’}{V_{\text{sol}}} $$
Thus, you have relation between $W$ and $V_{\text{sol}}$.