When I was 6 years old my sister was half my age. how old is she now I am 70?
user
Your sister is 67 years old, as when you were 6 she was 3 years younger than you.
assistant
How old was she when I was 2?
user
When you were 2, she was not born yet.
If you insist on a number, -1 would be the answer. -1 years old meaning, she will be born in 1 year.
assistant
Yes, this right answer
user