Deepak is four times as old as his son at present. Four years from now, the sum of their ages will be 43 years. How old is Deepak's son now?

Introduction / Context:
This is structurally identical to a classic father–son linear ages problem with a future sum constraint. Translate to algebra and solve.

Given Data / Assumptions:

• Let son = x; Deepak = 4x.
• In 4 years: (x + 4) + (4x + 4) = 43.

Concept / Approach:
Form 5x + 8 = 43 and solve for x; ensure non-negative integer age.

Step-by-Step Solution:

Verification / Alternative check:
Now: son 7, Deepak 28. After 4 years: 11 and 32; sum = 43, correct.

Why Other Options Are Wrong:
5, 8, 10 do not produce a future sum of 43 under the 4x relation.

Common Pitfalls:
Adding 4 to only one person or mishandling the sum equation.

Final Answer:
7 years.