4/3
21/80 is already in its simplest form
21 to 25
21/5 is the simplest form.
440/21 is in its simplest form.
21/10 is in its simplest form.
10/21 is in its simplest form.
4/21 is in its simplest form.
21/16 is in its simplest form.
21/52 is the simplest form.
21/100 is in its simplest form.
21/46 is the simplest form.
21/22 is in simplest form.