Dear Bashar,
Here is the solution for your query:
If a fraction is not in lowest term ,then we should take out the H.C.F. of the numerator and denominator of that fraction and divide that fraction with the H.C.F that you found.
Example:Suppose 12/24
H.C.F=2 x 2 x 3
=12
Then do this:
12/12=1
24/12=2
The answer would be 1/2.
Hope this answer helps you!!!!