Solve the system by the method of your choice x=3y-6,2x-6y=-12

The "system" of equations can't be solved for (x, y), because there's no "system" of equations given.  There's really only one equation.

Either of these two equations can be massaged to look exactly like the other one.  And if you graph both equations, you find that they're both the same line on the graph.

ANY point on the line is a solution to both equations ... and we all know how many different points there are on a line.

the battle of gettysburg is considered the "high water mark" of the confederacy because it marked the greatest advance of the confederate forces against the union.