The present-age ratio of A to B is 4 : 5. Four years from now, the ratio will be 14 : 17. What is B’s present age?

Introduction / Context:
Use present ratio to express ages as multiples and a future ratio to form a solvable equation for the multiplier.

Given Data / Assumptions:

• A = 4k, B = 5k
• (4k + 4) : (5k + 4) = 14 : 17

Concept / Approach:
Cross-multiply to get a linear equation in k, then compute B = 5k.

Step-by-Step Solution:

Verification / Alternative check:
Future ages: A = 28, B = 34 ⇒ 28 : 34 = 14 : 17, correct.

Why Other Options Are Wrong:
28 or 34 are not B's present age; “Data inadequate” is wrong because k is uniquely determined.

Common Pitfalls:
Reducing 28 : 34 incorrectly or forgetting to add 4 to both ages for the future ratio.

Final Answer:
30 yr.