3/4 = 9/12
12.25 = 12 1/4.
21
4/12 = 1/3
Think of it as a fraction: 4:12 is like 4/12, so if you simplify that it's 1:3.
11/12
4/5
6/8, 9/12, 12/16 and so on.
12 is an integer, not a fraction.
2/8, 3/12, 4/16, etc...
16/12=8/6=4/3
If I understand the notation correctly, then yes. 12/0.75 is 16.