Example: [tex] \frac{3}{5}+ \frac{4}{9} [/tex]
Look at the denominator of the fractions, and then see whether there is a common prime number associated with them.
In this example, since 5 and 9 (3*3) do not have any common prime numbers, you just multiply these numbers together and get 45.
There, we just found the LCD of fractions.
