Answer:
12 1/3 years
Explanation:
Let
x = his son's age
Grandpa Burk's age = 52 + x
In five years Grandpa Burk will be four Times as old as his grandson is now.
his son's age = 4(x + 5)
Grandpa Burk's age = 52 + x + 5
= x + 57
4(x + 5) = x + 57
4x + 20 = x + 57
4x - x = 57 - 20
3x = 37
x = 37 / 3
= 12 1/3 years
His son's age will be 12 1/3 years