Answer:
Let (x,y) be unknown endpoint.
Midpoint formula is given as [(x1+x2)÷2, (y1+y2)÷2]
[x+(-10)÷2, (y+4)÷2] = (-6,-4)
Compare the x coordinates and y coordinates of midpoint and endpoint.
(x-10)÷2 = -6 (y+4)÷2 = -4
x-10 = -6(2) y+4 = -4(2)
x-10 = -12 y+4 = -8
x = -2 y = -12
Hence, coordinates of endpoint is (-2, -12).