Proportional ages then and now: Neela is now three times as old as her daughter Leela. Ten years ago, Neela was five times as old as Leela. What is Leela’s present age?
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A25
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B30
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C15
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D20
Answer
Correct Answer: 20
Explanation
Introduction / Context:Present and past multiplicative relations between ages form a solvable system. Let present ages be in a simple ratio, then use the past condition to fix the scale.
Given Data / Assumptions:
- N = 3L (now).
- Ten years ago: N − 10 = 5(L − 10).
Concept / Approach:Substitute N = 3L into the ten-years-ago equation and solve for L.
Step-by-Step Solution:1) 3L − 10 = 5L − 50.2) Move terms: 40 = 2L ⇒ L = 20.3) Therefore Leela is 20 years old now (Neela is 60).
Verification / Alternative check:Ten years ago: 50 vs 10 → 5×. Now: 60 vs 20 → 3×. Consistent.
Why Other Options Are Wrong:They break either the present 3× or the past 5× condition.
Common Pitfalls:Forgetting both ages decrease by 10 simultaneously when moving to “ten years ago.”
Final Answer:20