Asolid has a mass of 30 grams and a volume of 10 cm 3 what is the density of the object

Density is simply the total mass of an object divided by the volume that the object occupies.  In your example you have an object of mass 30 grams which occupies a volume of 10 cubic centimeters (cm³). So the density μ= mass ÷ volume is (30 g)/(10 cm³) = 3 g/cm³, which is read as "3 grams per cubic centimeter). The Greek letter μ (mu) is commonly used to represent density.