The coordinates of D would be (3, -2)
In order to find this, we need to know that the value of E's points will always be the average of D and F's points. This is because it is the midpoint. Therefore we can use the following formula.
Value of x
(D + F)/2 = E
(D + 5)/2 = 4
D + 5 = 8
D = 3
Then we can do the same for the y values
Value of y
(D + F)/2 = E
(D + 8)/2 = 3
D + 8 = 6
D = -2
