Question 200
That's a tough problem for an 8 year old, I am rather impressed. After 26 years,   the brother of your cousin will be 12+26 years old, and your sister will be 14 + 26. So, your cousin will be 38 and your sister will be 40 (which is VERY old). The sum of their ages will be 78, half of that sum will be 39.