Respuesta :

6/18

3/9

12/36

5/15

4/12

Hi!

It can be many other numbers, but the best are that are in some connection with 18, but that are not bigger than 18, like this:

1/3 = 1*2/3*2 = 2/6

1/3 = 1*3/3*3 = 3/9

1/3 = 1*6/3*6 = 6/18

Hope this helps!