6.
[tex]\it \mathcal{V}=L\cdot\ell \cdot h=6\cdot4\cdot5[/tex]
7.
Fie n un astfel de număr .
[tex]\it n:3=4\ rest\ r \Rightarrow\begin{cases} \it n=3\cdot4+r \Rightarrow n=12+r\\ \\ \it r < 3 \Rightarrow r\in\{0,\ \ 1,\ \ 2\}\end{cases} \Rightarrow n\in\{12,\ \ 13,\ \ 14\}\\ \\ \\ S=12+13+14=39[/tex]
