"Three friends Anne, Bob and Chris work together to do a certain hob.
Channel: Doubtnut
Date: 05/04/2020

"Three friends
 Anne, Bob and Chris work together to do a certain hob. The time it takes them
 to do the work together is 6 hours less than Anne would have take alone, 1
 hour less than Bob would have taken alone and half
 the time Chris taken working alone. How long did it take them to complete the
 job, working together?
`20\ min`
b. `30\ min`
c. `40\ min`
d. `50\ min`"