Task: Question Answering
Input (English): Problem: a can do a piece of work in 10 days and b can do it in 15 days and c can do it 20 days. they started the work together and a leaves after 5 days and b leaves after 3 days from the beginning. how long will work lost ?
Options: a. 2, b. 4, c. 5, d. 6, e. 7
Output (English): d