Question

If A=(-1, 3] and B = [0, 4) then B-A​

Answer 1

I assume B - A means "the complement of A in B", or all the elements of B not belonging to A.

Then B - A = (3, 4), since A ∩ B is the interval [0, 3] and we omit this from the parent interval B = [0, 4).