midpoint formula : (x1 + x2)/2 , (y1 + y2)/2
(6,-2)....x1 = 6 and y1 = -2
(x,y).....x2 = x and y2 = y
sub
(6 + x) / 2 , (-2 + y) / 2
first, we find the x term...and since (1,3.5) is the midpoint, our x term has to be set equal to 1 (the x coordinate in the midpoint)
(6 + x) / 2 = 1
6 + x = 1 * 2
6 + x = 2
x = 2 - 6
x = -4
now, we find y...and since (1,3.5) is the midpoint, our y term has to be set equal to 3.5
(-2 + y) / 2 = 3.5
-2 + y = 3.5 * 2
-2 + y = 7
y = 7 + 2
y = 9
so point G is (-4,9) <==