Machine A can finish a job in 4 hours, Machine В can finish the job in 12 hours, and Machine С can finish the job in 8 hours. How many hours will it take for A, B, and С together to finish the job? Choose the correct choice from the following answers:	A) 15/4	B) 18/7	C) 21/8	D) 24/11	E) 28/13
The combined rate is 1/4+1/12+1/8 = 11/24 of the job per hour.   The time to complete the job is 24/11 hours.   The answer is 24/11.
<result>D</result>
Machine A can finish a job in 4 hours, Machine В can finish the job in 12 hours, and Machine С can finish the job in 8 hours. How many hours will it take for A, B, and С together to finish the job?