Answer:
( 1, -3 )
Step-by-step explanation:

To get this you would do 8x8 which equals 64
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.
You would subtract the tax first which 62.99-2.99=60$. Then you would divide the $60 left by 6 and 60 divided by 6 equals 10 so each shirt costs $10.