Hi!
If a graph has no solutions, the lines will be parallel.
Lines have "solutions" when they intersect with eachother. If there are no solutions, the lines will not intersect. Only parallel lines don't intersect.
If a graph has infinite solutions, the lines will be the same.
If a line has infinite solutions, they have to constantly be intersecting. That means the lines will have to be directly on top of each other, meaning they will be the same line.
SEE BELOW for graphs. First graph = NO SOLUTIONS; Second graph = INFINITE SOLUTIONS