Ta có:\(\frac{4}{9}=\frac{4\cdot6}{9\cdot6}=\frac{24}{54}\) ; \(\frac{6+9}{6\cdot9}=\frac{15}{54}\) ; \(\frac{2}{3}=\frac{2\cdot18}{3\cdot18}=\frac{36}{54}\)
=>\(\frac{15}{54}<\frac{24}{54}<\frac{36}{54}\)
=>\(\frac{6+9}{6\cdot9}<\frac{4}{9}<\frac{2}{3}\)