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:
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
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