Difficulty: Easy
Correct Answer: 56 years
Explanation:
Introduction / Context:This blends a past-sum constraint with a present ratio. Using the present ratio to express both ages, then applying the past-sum condition (subtracting 5 from each) yields a single equation for the scale factor.
Given Data / Assumptions:
Concept / Approach:Set up the linear equation in k and solve, then compute 4k for the father’s age. This keeps the algebra minimal while respecting both time points.
Step-by-Step Solution:
(4k − 5) + (k − 5) = 60 ⇒ 5k − 10 = 60 ⇒ 5k = 70 ⇒ k = 14Father = 4k = 56Verification / Alternative check:Five years ago: father 51, son 9; sum 60 as stated. Present ratio 56 : 14 reduces to 4 : 1.
Why Other Options Are Wrong:48/51/61 do not satisfy both the past sum and the present ratio simultaneously.
Common Pitfalls:Subtracting 5 from only one age or applying the ratio to the past instead of the present.
Final Answer:56 years
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