Question 229522
Tim does 1/30 of the job in 1 minute.
Sally does 1/45 of the job in 1 min.
Bob does 1/90 of the job in 1 min.
1/30 + 1/45 + 1/90 =
3/90 + 2/90 + 1/90 = 6/90
=1/15 of the job done by the 3 of them in 1 min.
15 min for the 3 of them to do the job.
.
Ed