You can
put this solution on YOUR website! If it takes 15 people 8 hours to clean a restaurant,
how long would it take 20 people?
First way:
It takes 15 people 8 hours. So it would take 5 people 24 hours.
(That's because 1/3 as many, or 5 people take 3 times as long, or 18 hours.)
It takes 20 people 6 hours. (Because 4 times as many people do it
in 1/4th the time.
Answer: 6.
Second way:
Or you can work it:
(people the first time)(hours the first time) =
(people the second time)(hours the second time)
15×8 = 20×N
6 = N
Edwin