SOLUTION:

Question 699530:
Answer by khv_maths(12) (Show Source): You can put this solution on YOUR website!
That's mean you are 4 years old and your sister is years old. = 2 y.o
So, when you was 2, your sister should be years old. = 1 y.o
Back to question, you are 100 years old, so, your sister should be years old.
So, the answer is