Question

janet is three years older than her sister julie.janets brother is eight years younger than their sister julie.the sum of all of their ages is 55 years

Answer 1

if Janet = Julie + 3
Janet Bro = Julie - 8
and Janet + Janet Bro + Julie = 55

Janet is 23.
Julie is 20.
Janet's brother is 13.

Answer 2

Let's name Janet's age x

julie is then x-3 years old

and the brother is x-3-8=x-11

and all three of them: x+x-3+x-11 are 55

so we count:

2x-3+x-11=55
3x-3-11=55
3x-14=55

add 14 5o both sides:

3x=69

divide by 3:
x=23

so Janet is 23, Julie is 23-3=20 and the brother is 20-8=12 years old!