3.
chiều rộng là : \(\dfrac{9}{2}-\dfrac{4}{3}=\dfrac{27}{6}-\dfrac{8}{6}=\dfrac{19}{6}\left(m\right)\)
nửa chu vi là : \(\dfrac{9}{2}+\dfrac{19}{6}=\dfrac{27}{6}+\dfrac{19}{6}=\dfrac{46}{6}\left(m\right)\)
4.
\(=\left(\dfrac{13}{8}+\dfrac{11}{8}\right)+\left(\dfrac{7}{6}+\dfrac{5}{6}\right)\\ =\dfrac{7}{4}+2=2\dfrac{7}{4}\)
