A square farm of side 240 meters has a small rectangular area for barn construction. This barn area has its length 10 meters more than its breadth and its area measures one-eighth the square farm. How much the owner has to spend to build a wall around the barn area at rate of Rs. 1.5 per meter?

• A. Rs. 510
• B. Rs. 470
• C. Rs. 3500
• D. Rs. 980