Zad. 21
[tex]a=20cm=2dm\\V=a^3=(2dm)^3=8dm^3\\8dm^3-3\frac12dm^3=4\frac12dm^3=4\frac12l\\Odp. C[/tex]
Zad. 22
[tex]15:00+2.5h=17:30\\Odp. C[/tex]