The easiest way to solve this will be to put the question in the slope-intercept form, y=mx+b. Then the y-intercept will be b.
2y-4x=-12
2y=4x-12
y=2x-6
So the y-intercept is -6.
6x-2x-6xy-2x-2y4x-2y=2x-2y-14xy
Unfortunately, limitations of the browser used by Answers.com means that we cannot see most symbols. It is therefore impossible to give a proper answer to your question. Please resubmit your question spelling out the symbols as "plus", "minus", "equals" etc. However, it appears as if the two equations are essentially the same and therefore there are infinitely many solutions.