a hypothetical element $"$X$"$ has two naturally occuring isotopes: $69\mathrm{.}17\%$ is with an isotope mass of $62\mathrm{.}93$ amu, and $30\mathrm{.}88\%$ is with an isotope mass of $64\mathrm{.}93$ amu. Calculate the atomis weight for $"$X$"$