Answer:
24
Step-by-step explanation:
If it took 3 hours to clean 6 houses than you can figure that is 2 houses per hours. so if there are 12 hours and 2 houses an hour, you multiply 12x2 and get 24. Another way to do it is to use proportions (aka two fractions that equal eachother):
3 hours 12 hours
---------------- = ---------------
6 houses number of houses
To calculate this, we can think about how we go from 3 to 12. Well, 3x4 is 12, so we got to 12 by doing multiplying by 4. So we can multiply 6 by 4 and you get 24.
Hope it helps! have a great day :)