If it takes 4 friends 4 minutes to eat cheeseburgers

If it takes 4 friends 4 minutes to eat cheeseburgers, how long will it take them to eat 80 cheeseburgers?

Answer: One cheeseburger takes 4 minutes to finish. Then 80 burgers divided by 4 people is 20 burgers each.

20 burgers times 4 minutes equals 80 minutes per each person. So if they start together and eating velocity remains constant it takes 80 minutes for them.