A father is now three times as old as his son. Five years back, he was four times as old as his son. The age of the son (in years) is:

🧠 Explanation:

A father three times his son’s age now, and five years ago four times, means the son is 15. Solve: if son’s age is x, father is 3x. Five years ago, 3x - 5 = 4(x - 5), so x = 15. This teaches algebra for age problems.