Let's find the volume of the rectangular prism:
[tex]\begin{gathered} V=l\cdot w\cdot h \\ where \\ l=3\operatorname{cm} \\ w=2\operatorname{cm} \\ h=1\operatorname{cm} \\ so\colon \\ V=3\cdot2\cdot1 \\ V=6cm^3 \end{gathered}[/tex]
The density is given by:
[tex]\begin{gathered} \rho=\frac{m}{V} \\ so\colon \\ \rho=\frac{120}{6} \\ \rho=\frac{20g}{cm^3} \end{gathered}[/tex]
