Ravi can do a piece of work in 15 hours while Raman can do it in 12 hours. How long will both take to do it, working together?

Number of hours Ravi required do a piece of work : 15 hours


Number of hours Raman required do a piece of work : 12 hours


Work done by Ravi in one hour:


Work done by Raman in one hour:


Work done by Ravi and Raman together in one hour: = =


They can do the work together in hours = = 6 hours 40 min


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