"Keep, change, flip"
Keep the first fraction, change the division sign into multiplication, then flip the second fraction... Then multiply
For example,
[tex] \frac{1}{2} / \frac{1}{4} [/tex]
keep, change, flip
[tex] \frac{1}{2} * \frac{4}{1} [/tex]
That will result in [tex] \frac{4}{2} [/tex] or simplified: 2
