questioning

A girl went to school and the teacher asked how old are you?

She replied I don’t know but I know that I’m half my mother’s age.

The teacher asked OK how old is your mother?

She said:- I don’t know but I know that my dad is 5 Years older than my mother.

The teacher, then ask how old is your dad?

She said I don’t know but I know that if we add our ages the answer is 100 yrs…

Now how old is the girl, her mum, & her dad?