An unknown substance has a volume of 6.7 cm3 and a mass of 75.7 g .

Answer 1

So, what's the question? Did you mean to ask what is the density of the unknown substance? Density is defined as mass per unit volume (mass/volume). The volume is 6.7 cm^3 (6.7 ml), and the mass is 75.7 g. You should be able to now find the density.