the proportions are:
[tex]\begin{gathered} 6\colon3 \\ 16\colon4 \end{gathered}[/tex]now we can divide the terms to see if they are proportional so:
[tex]\begin{gathered} \frac{6}{3}=2 \\ \frac{16}{4}=4 \end{gathered}[/tex]So they are not proportional