POW – Working Together

Both Don and Juan and are given a task on which they must work together to complete in a timely fashion. It takes Don 75 minutes to do the job by himself. It takes Juan 60 minutes to do the job by himself.

1. At their speed, how long would it take both Don and Juan to work together to get the task done? What formula could you use if you had to substitute each person’s time for a letter?
2. If Guadalupe, who takes 68 minutes, also helps, how long would it take all three to work together to get the task done? What formula could you use if you had to substitute each person’s time for a letter?

The answer for this Problem of the Week can be found here.