X can do a work in 15 days, while Y can do the same work in 10 days and Z can do the work in 30 days. They started the work together after 2 days X and Y together left the work. In how many days will be needed to complete the remaining work for Z alone?
1
30 days
2
18 days
3
40 days
4
15 days
5
25 days