Task: Question Answering
Input (English): Problem: a can do a job in 20 days and b can do it in 30 days. a and b working together will finish thrice the amount of work in - - - - - - - days ?
Options: a. 22 days, b. 22 days, c. 36 days, d. 72 days, e. 24 days
Output (English): c