A line segment has one endpoint at (6, 8) and midpoint at (-1, -1). What is the sum of the coordinates of the other endpoint?
+240 The formula of a midpoint of two points is just the average of the x, the average of the y.
\((\frac{(6+x)}{2},\frac{(8+y)}{2}) = (-1, -1) \\ 6+x = -2 \\ 8+y = -2 \\ x = -8 \\ y = -10\)
-8 + -10 = -18
