Answer:
None.
Explanation:
For graphs of a system, the 'solutions' are points where the graps intersect each other.
Here, the graphs are parallel, so there are NO intersections = no solutions.
If they intersected at one point, there would be one solution.
If they were really the same line, they would intersect all along the infinite line, so there would be an infinite number of solutions.
In a plane, those are the only three coices for two lines.