Task: Question Answering
Input (English): Problem: a can do a work in 15 days and b in 20 days. if they work on it together for 7 days, then the fraction of the work that is left is
Options: a. 8 / 17, b. 7 / 15, c. 3 / 15, d. 8 / 15, e. 11 / 60
Output (English): e