Let x be the unknown value.
Therefore we have
[tex]\frac{2}{4}=\frac{x}{16}[/tex]So we can inform from the first term that the denominator is double the numerator, since this term is equal to second term with the unknown x, same applies there also.
So,
[tex]\begin{gathered} 2x=16 \\ x=\frac{16}{2}=8 \end{gathered}[/tex]This can be further confirmed by applying cross multiplication,
[tex]\begin{gathered} \frac{2}{4}=\frac{x}{16} \\ 16\times2=4x \\ x=\frac{16\times2}{4}=8 \end{gathered}[/tex]