So a over b divided by c over d looks like the following
[tex]\frac{a}{b}\div\frac{c}{d}[/tex]
In order to divide two fractions, you multiply by the reciprocal (also known as the multiplicative inverse).
The reciprocal is the fraction "flipped"
[tex]\frac{a}{b}\div\frac{c}{d} = \frac{a}{b}\times\frac{d}{c}\\\frac{a}{b}\times\frac{d}{c} = \frac{ad}{bc}[/tex]
