Multiplication and division of fractions

Multiplication 
In general, when we multiply fractions, we multiply
the two numerators (the top numbers) to make the new
numerator, and multiply the two denominators to make
the new denominator.
For example:

7       4  
---- * -----
5       3


  7 * 4  
= --------
  5 * 3

   28
=  -------
   15


Division


7       4  
---- / -----
5       3

We can change this to multiplication by
simply changing the second fraction like,

7       3  
---- * -----
5       4


  7 * 3  
= --------
  5 * 4

    21
=  -------
    20