59/12 is in its simplest form.
6/11
11 over 12 is in its simplest form, and cannot be reduced further.
It isn't, it can be reduced to 1/3.
52/48 = 13/12 = 11/12 or 1.5
Expressed as a top-heavy fraction in its simplest form, 18/12 = 3/2 or three over two.
12/25 IS the simplest form, meaning it cannot be reduced.
12 over 25 in simplest form is 12 over 25. The prime factors of 12 are 2, 2, and 3. The prime factors of 25 are 5 and 5. There is no intersection, so the fraction cannot be further reduced. If you wanted it in decimal, 12 over 25 is 0.48.
4/5
15/12 = 5/4
12/17 is in simplest form.
7/12 is in its simplest form.