I'm not 100% sure if I am right, but for number 9 you would pick two points on , let's just say you pick points (0, 1) and (2, -2). Then you would find those points in the table. So in this case the answer would be D. And I'm not really sure how to explain #10 but you basically work out each problem with the graph to see if it makes sense. For example if you try working out problem F it wouldn't make sense since you start of with 10 dollars and earn 2 each day. But on the graph it shows that you are loosing two. Sorry if I didn't explain it right, if you have more questions let me know!
Centimeters might be easier because they can be much more precise than inches when there isn't an ideal length. Kilometers might be easier because it would not require such large numbers to work with.