> Adam can mow a field in 1 hour, in the same time Bob can mow 2 fields, if they work together how long does it take them to mow a field? Fred Brooks version:

> Adam can mow a field in 1 hour, in the same time Bob can mow 2 fields, if they work together how long does it take them to mow a field? Fred Brooks version: Amy can bear a child in 9 months. Bella also can bear a child in 9 months. If you assign both of them to bear a child, how long will it be before a child is born?