A very simple rule:
Whenever you a dividing a number (or fraction) by a fraction, you simply multiply the number (or fraction) by the reciprocal of the dividing fraction.
As an example, let's take a look at dividing a fraction by another fraction:

This division can be performed by multiplying 2/5th by the reciprocal of (2/3)rd, which is 3/2. Thus, it can be performed by:
