A father can do a job as fast as his two sons working together. If one son does the job in 3 hours and the other in 6 hours, how many hours does it take the father to do the job?. 1) 1 2) 2 3) 3 4) 4
A father can do a job as fast as his two sons working together. If one son does the job in 3 hours and the other in 6 hours, how many hours does it take the father to do the job?.
1) 1
2) 2
3) 3
4) 4