a, Ta có: \(\dfrac{27}{37}< \dfrac{27}{18};\dfrac{27}{18}< \dfrac{28}{18}\Rightarrow\dfrac{27}{37}< \dfrac{28}{18}\)
b, Ta có: \(1-\dfrac{2003}{2005}=\dfrac{2}{2005}\)
\(1-\dfrac{2001}{2003}=\dfrac{2}{2003}\)
Vì \(\dfrac{2}{2005}< \dfrac{2}{2003}\Rightarrow\dfrac{2003}{2005}>\dfrac{2001}{2003}\)