What is the total number of atoms present in fcc unit cell?

Calculate the void volume of simple cubic unit cell if the volume of unit cell is $5.5 \times 10^{-22} \mathrm{~cm}^3$.

Calculate the number of atoms in 0.3 gram metal if it forms bec structure $\left[\rho \times \mathrm{a}^3=3 \times 10^{-22} \mathrm{~g}\right]$

What is the total number of different types of unit cells present in triclinic crystal system?