Mr. Sohanlal is four times as old as his son at present. Four years from now, the sum of their ages will be 43 years. What is the son’s present age (in years)?

Introduction / Context:
Ages problems often give a present-time multiplicative relation and a future/past sum or difference. Translate the words into linear equations and solve systematically.

Given Data / Assumptions:

• Let son's present age = x years.
• Father (Mr. Sohanlal) is 4 times the son: father = 4x years.
• In 4 years: (x + 4) + (4x + 4) = 43.

Concept / Approach:
Form a single linear equation from the future sum and solve for x. Validate against given constraints (ages positive, integers typically).

Step-by-Step Solution:

Verification / Alternative check:
Father now = 4x = 28. In 4 years: son 11, father 32; sum = 43, correct.

Why Other Options Are Wrong:
5, 8, 10 produce future sums ≠ 43 under the 4x relationship.

Common Pitfalls:
Adding 4 only once or forgetting to add 4 to both father and son in the future-sum equation.

Final Answer:
7 years.