The volume is 36 g/cm^3.
Explanation: For this particular equation, you would use the volume formula of p=m/V. You would then rearrange this formula to look like V=m/p so that you can solve for the volume.
p=density
m=mass
V=volume
Once you have set up your equation, all that is left to do is plug in the values to your formula and solve, here is the work so that your understand.
V=m/p
V=18/0.5
V=36
Therefore, the volume is 36 g/cm^3.
Hope this helped!
