Worker A takes 8 hours to do a job. Worker B takes 10 hours to do the same job. How long should it take both A and B, working together but independently, to do the same job?

Q.

Worker A takes 8 hours to do a job. Worker B takes 10 hours to do the same job. How long should it take both A and B, working together but independently, to do the same job?

Q. Two workers A and B are engaged to do a piece of work. Working alone. A takes 8 hours more to complete the work then if both worked together. On the other hand, working alone, B would need $4\frac{1}{2}$ hours more to complete the work then if both worked together. How much time would they take to complete the job working together ?

Q. Ratan takes 5 days to complete a certain job and shankar takes 8 days to do the same job. If both of them work together, how long will they take to complete the work ?

Q. A can do 40% of a job in 12 hours. B is 16.67% more efficient than A. C is 28.57% less efficient than B. How long would the three of them take to do the job together?

Q. A man can do a job in $h$ hours alone and his son can do it in $2h$ hours alone. Together, how many hours will it take them to do the job?