If you solve a system and end up with the equations $\displaystyle{x}={0}\usepackage{cmbright}\Huge\$ and $\displaystyle{y}={0}\usepackage{cmbright}\Huge\$ , then the solution is (0, 0). Here, if you multiply the second equation by 10 and add it to the first equation, then you end up with $\displaystyle{0}={0}\usepackage{cmbright}\Huge\$ , which means something very different. This is true regardless of the value of x or y. The correct answer is: There are an infinite number of solutions.