The answer is
[tex]0.11g/cm^3[/tex]
Formula
[tex]Volume = Length * Width * Height[/tex]
[tex]Density = Mass/ Volume[/tex]
[tex]Volume = 5 * 15 * 3[/tex]
[tex]Volume = 225 cm^3[/tex]
[tex]Density = 24g/ 225 cm^3[/tex]
[tex]Density = 0.106 gcm^{-3}[/tex]
So, The answe is
[tex]0.11 gcm^{-3}[/tex]