Two motor mechanics, Raju and Siraj, working together can overhaul a scooter in 6 hours. Raju alone can do the job in 15 hours. In how many hours can Siraj alone do it?

Number of hours Raju required to overhaul a scooter : 15 hours

Let number of hours siraj required to overhaul a scooter : X hours

Number of hours required by Raju and Siraj together to do a piece of work : 6 hours

Work done by Raju in one hour:

Work done by Siraj in one hour:

Work done by Raju and Siraj together in a one hour :

Work done by Raju and Siraj together in one hour : = =

⇒ 6X +90 = 15X

⇒ 9X = 90

⇒ X = = 10 hours

Siraj can do the work 10 hours.