If it took 5 hours to clean 10 houses, how many houses could be cleaned in 9 hours?

18 houses

Step-by-step explanation:

First, find out how many houses they can clean in 1 hour.

10/5=2

They can clean 2 houses in 1 hour.

With this information,  you can now multiply the number of houses in 1 hour by 9 hours to find out how many houses are cleaned in 9 hours.

9*2=18

Therefore they can clean 18 houses in 9 hours.

explanation:

previous steps have made pa≅ pb ≅ st ≅ su. setting the compass width to ab allows you to make tu the same length. then δstu ≅ δpab by the sss congruence postulate, and ∠p ≅ ∠s by the reason cpctc.