Answer:
4 g / cm^2
Explanation:
The density is defined is
[tex]p=\frac{M}{V}[/tex]where m is the mass of the object and V is its volume.
Now in our case, we see that the cube weighs M = 240 g and has a volume of
[tex]V=3\operatorname{cm}\times5\operatorname{cm}\times4\operatorname{cm}=60\operatorname{cm}^3[/tex]With the value of M and V in hand, we now calculate the density
[tex]p=\frac{240g}{60\operatorname{cm}^3}[/tex][tex]p=\frac{40g}{\operatorname{cm}^3}[/tex]which is our answer!