E (3.75,-2.5)
G(-0.75, -3)
Point E is the midpoint of the segment AB, then it has coordinates:
(-3+6/2, -1+(-3)/2)= (3/2,-2)
Point F is the midpoint of the segment EB, then it has coordinates:
(3/2+6/2, -2+(-3)/2)= (15/4,5/2)= (3.75, -25)
Let S be the midpoint of segment CB, then it has coordinates:
(-3+6/2,-3+(-3)/2)= (3/2,-3)
Point G is the midpoint of segment CS, then its coordinates are:
(3/2+6/2, -3+(-3)/2)=(-3/4,-3)= (-0.75,-3)
Hope this helps!