Problems on Ages — “Hari is twice as old as Johnny. Johnny is 3 years older than Rahul. If Hari is 5 times Rahul, find Johnny’s age.”

Introduction / Context:
This is a classic three-person relation where one multiplicative statement (Hari vs Rahul) is combined with another multiplicative statement (Hari vs Johnny) and an offset (Johnny vs Rahul). Small integer solutions usually emerge cleanly.

Given Data / Assumptions:

• Let Rahul = r.
• Johnny = r + 3.
• Hari = 2 * Johnny = 2(r + 3).
• Hari is also 5 * Rahul = 5r.

Concept / Approach:
Equate the two expressions for Hari and solve for r, then compute Johnny = r + 3.

Step-by-Step Solution:

Verification / Alternative check:
Rahul 2, Johnny 5, Hari 10. Check: Hari = 2 * Johnny ⇒ 10 = 10 ✓; Hari = 5 * Rahul ⇒ 10 = 10 ✓; Johnny = Rahul + 3 ⇒ 5 = 2 + 3 ✓.

Why Other Options Are Wrong:
2/4/6/8 do not satisfy all three constraints simultaneously.

Common Pitfalls:
Setting Hari = 2r instead of 2(r + 3); or forgetting that the +3 applies to Johnny relative to Rahul.

Final Answer:
5 years