Question 107345
You were given the two points (-7,-6) and (-8,8) and were asked to find the coordinates of
the midpoint of the line joining these two points.
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The x value of the midpoint is found by averaging the x values of the two points. In other words
add the two given x-values and divide by 2. The x value of the first point is -7 and the
x-value of the second point is -8. Add these two values and you get -15. Then divide by
2 and you get that the x-value of the midpoint is -15/2. This is enough to tell you that the 
answer is "c" because it is the only answer with -15/2 in the x-position. 
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But just to make sure that "c" is correct let's also average the y-values of the two points to
find the y-value of the midpoint.  The y-value of the first point is -6 and the y-value of
the second point is +8. When you algebraically add -6 and +8 you get +2 and then divide by 2
to get +1. This tells you that the y-value of the midpoint is +1. That value is in the y-position
of answer "c". Therefore, this helps to confirm that answer "c" is the correct answer.
The midpoint is located at (-15/2, +1).
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Hope this helps you to understand this problem.