\[\frac{5}{12}\ и\ \ \frac{4}{9} \Longrightarrow \frac{15\ и\ 16}{36} \Longrightarrow \frac{15}{36} < \frac{16}{36} \Longrightarrow\]
\[\Longrightarrow \frac{5}{12} < \frac{4}{9}.\]