Answer:
The first set of ordered pairs is a function, because no two ordered pairs have the same first coordinates with different second coordinates. The second example is not a function, because it contains the ordered pairs (1,2) and (1,5).
Hope this helps you with your question.
Answer:
Mean = 19.5
Step-by-step explanation:
Mean = sum of numbers ÷ Amount of numbers
Mean = 
Mean = 
Mean = 19.5
Symmetric property of an Equality
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.