Explanation:
Let the ages of the 4 brothers three years ago be a, b, c, and d. The sum of their ages three years ago is x:
x = a + b + c + d
In five years, their ages will be a + 8, b + 8, c + 8, and d + 8. The arithmetic mean of their ages in five years will be:
[(a + 8) + (b + 8) + (c + 8) + (d + 8)] / 4
Simplifying:
(a + b + c + d + 32) / 4
We know that a + b + c + d = x (from the given information), so substituting:
(x + 32) / 4
Therefore, the answer is A) X/4 +8.