Question 19283
Hello There:

In work problems like this, we need to approach is in terms of how much of the job is done per unit of time.

Sally paints the garage in 8 hours, so each hour she completes 1/8th of the job.

Susan paints the garage in 6 hours, so each hour she completes 1/6th of the job.

Working together, they complete (1/8 + 1/6)th of the job per hour.

1/8 + 1/6 = 7/24

Completing 7/24ths of the job each hour means that it takes 24/7th hours when working together.

24/7 = 3.4286

0.4286*60 = 25.7

It takes them 3 hours and 25.7 minutes to do the job.

~ Mark