What is the factor of (attached image)

I believe that an answer without an explanation is no help.  This answer, however,
is the result of the combination of the seat of my pants and the top of my head,
so I'm afraid that no cogent explanation can be given.  Here's the

The factored form of  [ 16x - 2x - 3 ]  is  (2x-1)(8x + 3) .

To find out what the x value is at this specific point, all you have to do is input the y value into the equation. 

If you do this, it becomes:

-2 = -2x + 4 (y is inputed into the equation)
-2x = -6 (you minus 4 from both sides)
x = 3 (divide both sides by -2)

Hence the missing value is 3, Coordinates are therefore (3, -2)