Answer:
B(8, 1)
Step-by-step explanation:
M is the midpoint of AB so:
[tex]x_B-x_M=x_M-x_A\qquad\quad\ \wedge\qquad y_B-y_M=y_M-y_A\\\\x_B-1=1-(-6)\qquad\quad\wedge\qquad\quad y_B-(-3)=-3-(-7)\\\\x_B=1+6+1\qquad\quad\ \wedge\qquad\quad y_B=-3+7-3\\\\x_B=8\qquad\qquad\ \wedge\qquad\qquad y_B=1[/tex]
