Problema Solution
There are 600 dishes that need to be rinsed. John can rinse them in 120 minutes by himself. It will take his friend Bob 60 mins to rinse the dishes. How long will it take them if they rinse these 600 dishes together?
Answer provided by our tutors
together they will rinse in 1/(1/60 + 1/120) = 120*60 / 180 = 40
40 minutes