Let x represent the age of Gabrielle
Gabrielle's oldest brother jake is twice her age, This means that the age of her oldest brother is 2 * x = 2x
Her younger sister Candi is 4 years old.
Gabrielle has another brother,Tom, who is 6 years older than her. This means that the age of the brother is x + 6
Given that the brother is also two years younger than Jake, it means that the age of the brother is also
2x - 2
This means that
x + 6 = 2x = 2
2x - x = 6 - 2
x = 4
Therefore, the sum of the ages of all the siblings is
x + 2x + 4 + x + 6
= 4 + 2 * 4 + 4 + 4 + 6
=4 + 8 + 4 + 4 + 6
= 26 years
The sum of their ages is 26 years