Respuesta :

Call M the midpoint. The coordinate of this point is given by....

M=(x1+x2 /2, y1+y2 /2)

So (3,7)=(x1+0 /2, y1+ -5 /2). or

3= x1/2. or x1=6 and

7=y1-5 /2. or 14=y1-5 or y1=19

B is at the point (6,19)