Assuming your system of equations is
The answer is C. Infinitely many solutions. If my assumption is incorrect, then the answer will be likely different.
The reason why it's "infinitely many solutions" is because the first equation is the same as the second equation. The only difference is that everything was multiplied by -1. You could say that both sides were multiplied by -1.
Both equations given graph out the same line. They overlap perfectly yielding infinitely many solution points on the line.