Question 724028
If a line is perpendicular to the x-axis, then
for every point on the line, ( x,y ), it sees the same 
x no matter what y is.
In your problem
{{{ x = -23 }}}
That is the equation. ( -23,15) is just 1 point on the line.
Other points would be ( -23, 571246 ), ( -23, -8341 )
etc, etc, etc