Set the coordinates for the other endpoint as (x, y).
Use the formula for midpoint:
(x1+x2)/2 + (y1+y2)/2 = (x, y)
Solution:
(x+5)/2 + (y+2)/2 = (-1,10)
(x+5)/2 = -1
x+5 = -1(2)
x+5 = -2
x = -2-5
x = -7
(y+2)/2 = 10
y+2 = 10(2)
y+2 = 20
y = 20-2
y = 18
The coordinates for the other endpoint are (-7,18) .
