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?
Ravi's one hours work =115
Raman's one hour's work =112
Both's one hour's work =115+112
=4+560=960=320
∴ BOth can finish the work in
203=623 hours or 6 hours, 40 minutes.