If there were no significant interactions would be additive (using data from mass and volume), but there may be a considerable deviation, depending on the type of interaction.
1. for an ideal solution, as stated in the previous answer, the volumes of the liquids (assuming that the solvent and solutes A and B are liquid) are additive and, in that case (and only in that case), you can obtain an approximate value for density provided that the temperature at which the volumes of A and C were measured is the temperature at which density values were obtained;
In that case:
Vm= xAVA* + xBVB* + xCVC*, where x stands for mole fraction (xi=ni/ntotal) and Vi* are the molar volumes of the pure components;
Vm and Vi*= d(density)/M(Molar mass);
Therefore, a rough value for density is: dsolution= Vm*M