Answer:
21 hours
Step-by-step explanation:
We can use a ratio to solve
7 houses 30 houses
------------- = --------------
5 hours x hours
Using cross products
7x = 5*30
7x = 150
Divide by 7
7x/7 =150/7
x =21.42857143
Rounding to the nearest whole number
x = 21 hours
