when a variable is eliminated, then the two possible solutions are either infinite solutions or no solutions.
2x + 3 = 2x + 3
2x - 2x = 3 - 3
0 = 0
In this case, we have a true statement....this means that the problem has infinite solutions.
2x + 3 = 2x + 9
2x - 2x = 9 - 3
0 = 6
In this case, we have a false statement...this means the problem has no solutions