The installation cost of a machine is Rs. 2000. The cost of repairs increases Rs. 40 annual). The scrap value of the machine is Rs. 200. The economic repair life of the machine is nearly:

• A. \[5\frac{1}{2}\] Years
• B. \[7\frac{1}{2}\] years
• C. \[9\frac{1}{2}\] Years
• D. \[11\frac{1}{2}\] years