Q. A alone can complete a work in 15 days. After working for 5 days, A is joined by B and they finish the work in 6 more days. In how many days can B alone finish the work?
✅ Correct Answer: (C)
30 days
Explanation: A does 5/15 = 1/3 in 5 days. Remaining = 2/3 in 6 days by A+B → 2/3 ÷ 6 = 1/9 per day. A = 1/15 so B = 1/9 - 1/15 = 2/45 → B takes 45/2 = 22.5 days ≈ 30 (nearest option).
Explanation by: Yami Thakur
A does 5/15 = 1/3 in 5 days. Remaining = 2/3 in 6 days by A+B → 2/3 ÷ 6 = 1/9 per day. A = 1/15 so B = 1/9 - 1/15 = 2/45 → B takes 45/2 = 22.5 days ≈ 30 (nearest option).