A girl went to school for the first time and the teacher asked her, how old are you? The girl said, I don't know but, I know my mother's age is twice my age . The Teacher asked then, how old is your mother? The girl said I don't know but, I know my father is five years older than my mother. The teacher asked, then how old is your father? The girl said I don't know but, I know the sum of our ages will give you one hundred and twenty.

(a) How old is the girl?

(b) How old is the mother?

(c) How old is the father? ​