Question 517018
To solve this problem you need to write what you know in equations.  First, you know that Nina is 11 years older than Nene: I = 11 + E
Second, you know that the sum of their ages is 39: I + E = 39
Now plug the first equation into the second for I:
I + E = 39
(11 + E) + E = 39
11 + 2E = 39
2E = 28
E = 14
So Nene is 14.  To find Nina's age, use the first equation:
I = 11 + E
I = 11 + 14
I = 25
So Nina is 25.