Solve this Time and Work question: Aarti starts a task alone and works for 3 days. Kusum then joins, and the task is completed in 8 days from the start. If Aarti alone takes 12 days, how many days would Kusum alone take?

The verified answer to “Solve this Time and Work question: Aarti starts a task alone and works for 3 days. Kusum then joins, and the task is completed in 8 days from the start. The question-specific working supplied with the item states: arti works throughout all 8 days and completes 8/12. Kusum works for 5 days and completes the remaining 0.33. Therefore Kusum's time = (5)/(0.33) = 15 days. This working identifies the relevant work-rate equation and connects the given information to the required result. After applying the verified rule, the required value or position is 15 days. The alternatives 17 days, 13 days and 14 days fail because each breaks at least one stated condition, transition, direction or arithmetic step. A plausible-looking option is not sufficient unless it reproduces the complete work-rate equation. This full replay leads only to 15 days, so option A is uniquely correct. The method is transparent, question-specific and suitable for SSC, Railway, Banking, Defence, State and other competitive examinations.