Task: Question Answering
Input (English): Problem: 5 drainage pipes, each draining water from a pool at the same constant rate, together can drain a certain pool in 12 days. how many additional pipes q, each draining water at the same constant rate, will be needed to drain the pool in 4 days ?
Options: a. 6, b. 9, c. 10, d. 12, e. 15
Output (English): c