Two Stable isotopes of lithium $^6_3Li$ and $^7_3 Li$ have respective abundances of $7.5\%$ and $92.5 \%$ These isotopes have messes $6.01512$ amu and $7.01600$ amu respectively . Find the atomic height of lithium

Question

$\begin{array}{1 1} 69.41\;amu \\ 694.1\;amu \\ 6.941 \;amu \\0.6941 \;amu \end{array} $