To determine how much will it take to clean a 120ft driveway considering that it took him 2hs to clear 10ft and that the cleaning rate is constant, you can use cross multiplication:
10ft______2hs
120ft_____xhs
If the cleaning rate is the same, then the ratios between both are the same:
From this expression, you can determine the time by multiplying both sides of the equal sign by 120
It will take him 24 hours to clear the 120ft driveway.