The coordinates of X would be (-27, 16)
In order to find this, we need to know that the value of M's points will always be the average of X and Y's points. This is because it is the midpoint. Therefore we can use the following formula.
Value of x coordinate
(X + Y)/2 = M
(X + 19)/2 = -4
X + 19 = -8
X = -27
Then we can do the same for the y values
Value of y coordinate
(X + Y)/2 = M
(X + 0)/2 = 8
X + 0 = 16
X = 16
