Difficulty: Medium
Correct Answer: 15 years
Explanation:
Introduction / Context:This problem mirrors the earlier two-equation pattern with past and future multiplicative age relations. Represent present ages with variables and translate the time-shifted statements into equations to solve cleanly.
Given Data / Assumptions:
Concept / Approach:Convert to present-age equations and solve simultaneously for x.
Step-by-Step Solution:
From past: y − 5 = 3x − 15 ⇒ y = 3x − 10. …(1)From future: y + 5 = 2x + 10 ⇒ y = 2x + 5. …(2)Set equal: 3x − 10 = 2x + 5 ⇒ x = 15.Ashu’s present age = 15 years.Verification / Alternative check:Five years ago Ashu 10, Mother 30 ⇒ 30 = 3 * 10 ✓; in five years Ashu 20, Mother 40 ⇒ 40 = 2 * 20 ✓.
Why Other Options Are Wrong:10/12/20/35 violate at least one of the two time-shifted multiplicative conditions.
Common Pitfalls:Applying the multiplier to current ages directly; forgetting to shift both ages by the same number of years when moving to past or future.
Final Answer:15 years
Discussion & Comments