[tex]\begin{gathered} 4\text{ pairs of black socks implies that there are 4}\cdot2\text{ =8 black socks} \\ 2\text{ pairs of grey socks implies that there are 2}\cdot2=4\text{ grey socks} \\ so\text{ the fraction is }\frac{8}{8+4}=\frac{8}{12}=\frac{2}{3} \end{gathered}[/tex]
