In a row 'A' is in the 11th position from the left and 'B' is in the 10th position from the right. If 'A' and 'B' interchange, then 'A' becomes 18th from the left. How many persons are there in the row other than 'A' and 'B'?

Let's think about this intuitively by focusing on the 'seats' rather than the people.\n\n1. **Look at the destination seat:** We know B is sitting in the **10th seat from the right**. Let's call this the 'Target Seat'.\n\n2. **The Swap:** A moves to this 'Target Seat'. The question now tells us that A is at the **18th position from the left**.\n\n3. **Combine the info:** This means the 'Target Seat' has two labels: it is 10th from the right AND 18th from the left.\n\n4. **Find the Total:** To find the total number of seats, we add the positions and subtract 1 (since we counted the 'Target Seat' twice).\n Total = 18 + 10 - 1 = **27 persons** in the row.\n\n5. **The Final Twist:** The question asks for the number of people *other than* A and B. \n So, we take our total (27) and remove A and B (2 people).\n Final Answer = 27 - 2 = **25**.