What are Empirical and Molecular Formulae? How are they related to each other?

An element $\mathrm{X}$ has the following isotopic composition:

${}^{200}\mathrm{X}:90\raisebox{1ex}{$ \mathrm{o}$}\!\left/ \!\raisebox{-1ex}{$\mathrm{o}$}\right.$ ,  ${}^{199}\mathrm{X}:8.0 \raisebox{1ex}{$\mathrm{o}$}\!\left/ \!\raisebox{-1ex}{$\mathrm{o}$}\right.$ ,   ${}^{202}\mathrm{X}:2 \raisebox{1ex}{$\mathrm{o}$}\!\left/ \!\raisebox{-1ex}{$\mathrm{o}$}\right.$

The weighted average atomic mass of the naturally occurring element $\mathrm{X}$ is close to :