If a man with type O marries a women with type AB what are the chances there first child will have type O

0 percent chance.

Explanation:

The woman will give off either an A or a B allele to her child; the man can only give off an O because that is all he has. So if the A is given from the woman, it will be AO, forcing the A to show. If a B is given from the woman, it will be BO, forcing the B to show. The child has a 50-50 shot at either being AO (A shown), or BO (B shown). There is no chance at being AB or O.