First you need to determine the mass of the glass. Then fill it with water and put it back on the balance. The density and mass of water in a glass determine its capacity. Having filled the glass with an unknown liquid, its mass is determined on the scales. Knowing the mass of the liquid in the glass and its volume, the density of the unknown liquid is calculated.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.