How long will it take steve to word process the paper alone?

Question

Alan can word process a research paper in 6 hours. With Steve's help, the paper can be processed in 4 hours. How long will it take Steve to word process the paper alone?

Answer 1

In 4 hours Alan does 4/6 or 2/3 of the job.

Than leaves 1/3 of the job for Steve who needs 4 hours.

Working alone Steve would need 12 hours (3 times 4)