The system of equations [tex] \left \{ {{3x + 15y = 9 } \atop {y = - \frac{1}{5} x + \frac{9}{15} }} \right. [/tex] has infinitely many solutions. This is because when you solve the first equation for y, you get the same equation as the second equation, meaning that they are the same line. Hence, we get the answer infinitely many solutions. Hope this helps!