Answer:
I believe it is because it does not start at 0

means you shade the part above the line, and

means you shade the part under the line.
If it has an equal bar under it, like this:

, then you also shade the line, by making it solid instead of dotting it.
Answer:
69%
Step-by-step explanation:
Overall grade = 0.35*minor grade + 0.65*major grade
major grade: 0.65*61 = 39.65
minor grade: 0.35*84 = 29.4
total: 39.65+29.4 = 69.05
Rounded = 69%
For it to be non-linear, the rate of change cannot be constant. For the first table the rate is a constant 1 and the second table has a constant rate of -1. The 3rd and 4th tables have no constant rate and thus are non-linear.
The 4th table is increasing while the 3rd table is decreasing.
So the 3rd table, Set C, is the only non-linear negative association between x and y.