How do you work out the simplest form of an fraction?

Test the numerator (top) and denominator (bottom) of the fraction for their highest (or greatest) common factor. If it is 1, then the fraction is in its simplest form. If not, divide each of them by their GCF. The result will be a fraction in its simplest form.

For example, 18/24

GCF(18, 24) = 6

18/6 = 3

24/6 = 4

So the simplest form of 18/24 is 3/4