Answer:
Afful is 21 and Naomi is 13. 
Explanation:
Let 
 represent the age of Afful and 
 represent the age of Naomi. 
The sum of their ages is 34. In other words: 

In 5 years time, Afful will be two times the age of Naomi now. In other words: 

Solve for the system. Substitute. 

Afful is currently 21 and Noami is currently 13.