A can complete a job in 20 hours. B alone can complete the same job in 15 hrs. A work for 9 hrs and then the remaining job is completed by B. How many hours will B be alone take to complete the remaining job?
The part of job that A completes in 9 hours = 9/20 Remaining job =1 - 9/20 = 11/20 Remaining job can be done by B in 11/20*15 = 33/4 = 8*1/4hrs