Answer:
D) Infinitely many
Step-by-step explanation:
Given system of equations
[tex]\left \{ {{6x+18y=9} \atop {y=-\frac{1}{3}x+\frac{1}{2} }} \right.[/tex]
Substitute second equation into first equation
[tex]6x+18y=9\\\\6x+18(-\frac{1}{3}x+\frac{1}{2})=9\\ \\6x-6x+9=9\\\\9=9[/tex]
Therefore, since both sides are equal to each other no matter what, there are infinitely many solutions.
You can confirm that there are infinitely many solutions by looking at the graph of both functions. They overlap each other, so every solution will work.