The age of a grandson is one-fifth the age of his grandfather. Twenty years later, the ratio of their ages would be (\frac{23}{35}). What is the present age (in years) of the grandson?

Let grandson's age = x, grandfather's age = 5x. After 20 years: (x+20)/(5x+20) = 23/35. Cross-multiply: 35(x+20) = 23(5x+20). 35x + 700 = 115x + 460. 80x = 240, so x = 3. Grandson is 3 years old, grandfather is 15. In 20 years they'll be 23 and 55, ratio = 23/55 ≠ 23/35. Wait, rechecking... Actually 5x+20 = 15+20 = 35, so ratio = 23/35. Correct!