William W. answered • 09/12/19

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The midpoint equations are x_{midpoint} = (x_{1} + x_{2})/2 and y_{midpoint} = (y_{1} + y_{2})/2

So, plugging in the given points yields: -9 = (x + -3)/2 and -2 = (y + 2)/2

-9 = (x + -3)/2

-18 = x - 3

x = -15

-2 = (y + 2)/2

-4 = y + 2

y = -6

So the coordinates of the other endpoint are (-15, -6)