Four people can mow a lawn in 6 hours. How many more people will be needed to mow the lawn in 4 hours, assuming each person mows at the same rate?

6 people

We can use the "see-saw" principle, here

4 people * 6 hours = x people * 4 hours

24 = x * 4 divide both sides by 4

24 / 4 = x = 6 people

Thanks!