A and B can complete a task in 25 days. B alone can complete 33 1/3%of the same task in 15 days. In how many days can A alone complete 4/5th of the same task?

B alone can complete 33.33 % task in 15 days.
 Part of task completed by B in 25 days is  25 × 33.33/15 = 55.55 %
Remaining 100-55.55 = 44.45 % task is completed by A in 25 days.
 So time required to complete 4/15th task is 25 × (4/15)/(44.45/100) = 15 days.

Hence option 2 is the correct answer.

By: Himani Bihagra