Simple...
you have
4-6=?
and
4-3=?
Well, if you know anything about negatives...you know that 6 is a bigger number than 4; and that if you subtract it, it becomes a negative...
4-6= -2
and
4-3=1
Now, which one is bigger?
Fairly easy...when a number is negative..that means it less than 1. Even smaller than 1.
So, that being said 4-3 is obviously bigger.
Thus, your answer.