Answer:
A - B = (0, 6)
or,
Considering
A = 9
B = 3
A - B = 6
I've taken this approach, but I don't know what solution is expected for this question. It seems to be open.
Explanation:
So, we have two intervals. I will consider both as open.
A= (0, 9) and B = (6, 9)
Taking:
A - B = (0, 6)