Here is one of the questions that I had trouble solving,

(1 C)

The mistake that I was making was that I subtracted x1 by y1, and x2 by x2. In other words, I did whatever was in the same bracket.

The correct way to do this question is to minus x1 by x2, and y1 by y2, then square each difference and add them together. If the end result is a perfect square, write it as that, but if it is not then leave it but put a root sign over it. Putting a root sign over the radical is more accurate than plugging in the radical in your calculator and trying to round the ugly number.

here is the correct answer,

(the final answer is 11, but it got cut off)