Question

There are 630 dishes that need to be rinsed. manuel can rinse them in 105 minutes by himself. it will take his friend carlos 70 minutes to rinse these dishes. how long will it take them if they rinse these 630 dishes together?

Answer 1

630/105=6 minutes per dish

630/70=9 minutes per dish

15 minutes:2 dishes

630/15=42

It will take them 42 minutes to rinse 630 dishes together.