Answer:
slope 4/5
Step-by-step explanation:
The attachment shows the rise in green (4 grid squares), and the run in red (5 grid squares). The slope is the ratio rise/run.
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The slope is rise/run = 4/5.
No, it does not and it's not supposed to. A trend line is drawn to go through in the best way possible, to go through the "center" of the points as best as it can. It may hit some of the points, but not all of them. Generally, the idea is to try to get the trend line to have as many points "above" it as it does "below" it to say you've gone through them evenly.
Y = 54.
This is really complicated to explain, but since x is 36 and the angle on the other side of the known angle is also 36, that makes y 54. Each pair of angles has to equal to 90 degrees.
Hope this helps!