A proportion means that two ratios are equal.
Let's see each ratio as a fraction, and simplify:
[tex]\begin{gathered} \frac{8}{27}\rightarrow\frac{8}{27} \\ \frac{12}{18}\rightarrow\frac{2}{3} \end{gathered}[/tex]Thereby,
[tex]\frac{8}{27}\ne\frac{2}{3}[/tex]The ratios don't form a proportion.
