The formula for calculating density is P=M/V where P is the density, M is the mass, and V is the volume.
The problem gives you the mass, 30g, and the volume, 60cm^3;you can plug those into the equation, which should give you P=30/60.
Your answer should end up being P=0.5 g/cm^3.
WORK:
P=M/V
P=30g/60cm^3
P=0.5g/cm^3
