Use [tex]\dfrac{\frac{a}{b}}{\frac{a}{c}}=\dfrac{ac}{ab}=\dfrac{c}{b}[/tex]
[tex]\dfrac{\frac{3}{6}}{\frac{3}{7}}=\dfrac{3\cdot7}{3\cdot6}=\dfrac{7}{6}[/tex]
Hope this helps.