Question

Rohan, Amit and Deb together complete a piece of work in 4 days. Rohan can do it alone in 12 days and Amit alone in 15 days. How many days will Deb take to complete the work if he works alone?

Answer 1

part of work done by all 3 =1/4
work of Deb=
1/4-(1/12+1/15)
1/4-9/60
(15-9)/60=6/60=1/10 part
Deb will complete work alone in 10days