the midpoint of CD is E (-1,0). one endpoint is C (5,2). what are the coordinates of the other endpoint

Answer 1

Let the other endpoint be (a,b)
so ...
(a+5)/2 = -1 and (b+2)/2 = 0
a+5 = -2 and b+2 = 0
a = -7, b = -2

then the other endpoint is (-7,-2)