Difficulty: Medium
Correct Answer: 20 years
Explanation:
Problem restatement
Use a system of equations with present ages and a past ratio to find the son's current age, then add 6 years.
Given data
Concept/Approach
Solve the linear system for S; the future age is S + 6.
Step-by-step calculation
F − 6 = 5S − 30 → F = 5S − 24 (5S − 24) + S = 60 6S = 84 → S = 14 After 6 years: S + 6 = 20
Verification/Alternative
Present father's age F = 60 − 14 = 46. Six years ago: 40 and 8, and 40 = 5 × 8 (satisfies the condition).
Common pitfalls
Final Answer
20 years
Discussion & Comments