The two points (-8,12) and (-13,-2) have x coordinates of -8 and -13. Add these x coordinates up to get
-8 + (-13) = -8 - 13 = -21
Now divide that result by 2 to get -21/2 = -10.5
This value is the x coordinate of the midpoint.
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The y coordinates of (-8,12) and (-13,-2) are 12 and -2
Add these values up to get 12+(-2) = 12-2 = 10
Now divide that result by 2: 10/2 = 5
The y coordinate of the midpoint is 5
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Answer: (-10.5, 5)