# In how many days B can finish the work alone? If

A can do in one day three times the work done by B in one day. They together finish 2/5 of the work in 9 days. The number of days by which B can do the work alone is:

- 100 days
- 30 days
- 90 days
- 120 days

**Answer: (3) 90 days**

**Explanation:-
**A can do in one day three times the work done by B in one day.

Then, A = 3 B

They together finish 2/5 of the work in 9 days.

Therefore, they together complete the work = 9 x 5/2

= 45/2 days

Then, 3/B + 1/B = 2/45

(3 + 1)/B = 2/45

4/B = 2/45

B = 4 x 45/2

B = 90 days

Then, the number of days by which B can do the work alone is 90 days.

Hence, the answer is (3) 90 days.