Part of this question contradicts itself, so I'm not sure what answer it's looking for.
12 + 7 = 19
19 + 8 = 27
27/3 = 9
So that makes perfect sense, but then it says "Nancy is two years younger than Cindy."
There is no possible way that can be true and Thea can be 3x older than her.
Something is wrong here.