How many days would it take the man who finishes the work if he does the work alone?

Question

Jatin and Nihal together can complete a work in 10 days. They plan to do the job in a different way. On the first day Jatin works whereas Nihal works for the next 2 days and this pattern is repeated again and again. If they finish the work in 18 days, then in how many days could the man who finishes the work do this work alone ?

Answer 1

Nihal can do it in 15 days.

If they finish in 18 days, it means that Nihal finishes the job (he works every 2nd and 3rd day of a 3-day shift, 18/3 is last day of 6th shift). During the 18 days, Jatin has worked 6 days and Nihal 12 days. They could also had finished the work if they both worked 10 days. That means that 2 days of Nihal (12-10) equals 4 days of Jatin (10-6).

The 10 days of Jatin could be done by Nihal in only 5 days. Add the original 10 days results in 15 days.

Answer 2

Answer - Jatin alone can complete the work in 30 days and Nihal alone can complete in 15 days.

Explanation can be posted if want.