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 6 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) 1 B) 2 C) 3 D) 4 E) 5
The combined rate is 1/4+1/12+1/6 = 1/2 of the job per hour.   The time to complete the job is   2/1= 
<gadget id="calculator">  2/1</gadget>
<output>2</output>
2 hours.   The answer is 2.
<result>B</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 6 hours. How many hours will it take for A, B, and С together to finish the job?