Task: Question Answering
Input (English): Question: Mangala completes a piece of work in 18 days, Raju completes the same work in 40 days. If both of them work together, then the number of days required to complete the work is

 Option A: 6 days

 Option B: 7 days

 Option C: 15 days

 Option D: 9 days

 Option E: 11 days
Output (English): Option C