Task: Question Answering
Input (English): Problem: a and b can finish a work in 10 days while b and c can do it in 18 days. a started the work, worked for 5 days, then b worked for 10 days and the remaining work was finished by c in 15 days. in how many days could c alone have finished the whole work ?
Options: a. 30 days, b. 15 days, c. 45 days, d. 24 days, e. none of these
Output (English): c