Keep in mind that:
[tex]\frac{a}{b}-\frac{c}{d}=\frac{ad-bc}{bd}[/tex]
So,
[tex]\frac{4}{7}-\frac{3}{6}=\frac{4.6-7.3}{7.6}[/tex]
[tex]\frac{24-21}{42}[/tex]
[tex]\frac{3}{42}[/tex]
[tex]\frac{1}{14}[/tex]
