If a babys blood type is b what would the parents blood type be?

Answer 1

possible

B and B
B and O
B and A
B and AB
AB and O
AB and AB
AB and A

not possible

A X A
A X O
O X O

Answer 2

You can't necessarily say what each of the parents is.
Basically each person has two "alleles," and one of these is donated to the baby:
An A parent could have AA or AO.
A B parent could have BB or BO.
An AB parent has an A and a B.
An O parent has OO.

So, if the baby is B, that means it has either two B's or a B & an O. Therefore, all you can tell is that both parents aren't A or O. One parent must be AB or B, or else there's no B allele to pass on.