Question

A, B, and C can complete a job in 20, 30, and 60 days respectively. How long will they take working together?

Solution

1. Their combined one-day work = 1/20 + 1/30 + 1/60.
2. Using denominator 60: 3/60 + 2/60 + 1/60 = 6/60 = 1/10.
3. They complete the job in 10 days.