Suresh can complete a job in 15 hours. Ashutosh alone can complete the same job in 20 hours. Suresh works for 9 hours and then the remaining job is completed by Ashutosh. How many hours will it take Ashutosh to complete the remaining job alone?	Choose the correct choice.
A) 4 B) 5 C) 8 D) 12 E) none of these

Rationale: the part of job that suresh completes in 9 hours = 9 â  „ 15 = 3 â  „ 5 remaining job = 1 - 3 â  „ 5 = 2 â  „ 5 remaining job can be done by ashutosh in 2 â  „ 5 ã — 20 = 8 hours answer c
Answer: C