Question 519389
mid point (x,y)

x= (x1+x2)/2

y= (y1+y2)/2

mid point (-5,1)
endpoint (-1,3)

-5=(x1+(-1))/2
-5*2=x1-1
x1=-9

1=(y1+3)/2
2=y1+3
y1=-1

endpoint =  (-9,-1)