So lets just forget about the whole #'s right now (don't worry, we will get back to that)
1 1
--- - ---
4 3
You have to find a common denominator.
What 3's can 4 and 3 make?
assuming you want the smallest one, it will be 12
You have to times the bottom by a number to make them 12, but what you do to the bottom, you must do to the top.
1*3 1*4
--- - ---
4*3 3*4
That makes:
3 4
--- - ---
12 12
Now that you have common denominators, you can treat this like a normal subtraction. (You cannot subtract the denominators though, or else what was the point of finding a common denominator?)
3 4 1
--- - --- = - ---
12 12 12
Now time to take your whole numbers:
3-2=1
Now since you have a negative number, you have to add that whole number you have.
1 12
- --- + ----
12 12
All you would have to do is minus one from the 12 from the top of the second fraction because of your negative, and your answer would be 11/12
Hope that wasn;t to complex, probably confused ytou more.