A: Have you got a brother?
B: Yes, I have. / No, I haven´t.
A: Have you got a sister?
B: No, I haven´t. / Yes, I have. What about you?
A: I have got one sister and one brother.
B: How old is your sister/brother?
A: She/he is (5). How old is your brother/sister?
B: He /she is (10).