Let the age of Maisie be x
From the first statement, Ellie is six years older than Maisie implying:

From the second statement, Zoe is twice as old as Eli implying:

From the last statement, the sum of their ages is 50 implying:

Solving for x:
We open the bracket and collect like terms

Hence, Zoe's age is:

Answer:
Zoe's age = 28