Arun can do a piece of work in 30 days Rohan who is 40 more efficient than arun can finish the work ...........

Explanation:

Answer & Solution
Answer – 150/7
Solution:
In one day  work done by arun is 1/30 and rohan is 40% more efficient than arun , so one day work of rohan = (140/100)*1/30 = 7/150.
So time taken by rohan will be 150/7