Older sister is 26, Mary is 13, and younger sister is 8.
Explanation:
26 + 13 + 8 = 47
If the older sister is 26, then Mary is half that, meaning: 26/2 = 13
Mary is 13, and her younger sister is 5 years younger so: 13-5 = 8
Her younger sister is 8.
To double check, add up the ages and see if you get 47.
26 (older sister) + 13 (Mary) + 8 (younger sister) = 47
