Note that [tex]A=lw[/tex], where [tex]A[/tex] is the area, [tex]l[/tex] is the length, and [tex]w[/tex] is the width. Substituting our values in, we have:
[tex]\frac{5w}{9} = \frac{25}{54}[/tex]
Multiplying by [tex]\frac{9}{5}[/tex] gives:
[tex]w=\frac{5}{6}[/tex]
So the width is [tex]\frac{5}{6}[/tex] miles.