SAT Question cd33b015: Systems of Linear Equations answer and explanation with Desmos solution

Choice A is incorrect. If $y=10$, then $x=10$ since $x+y=20$. However, substituting $10$ for both $x$ and $y$ in the second equation yields $70=85$, which is a false statement.

Choice C is incorrect. If $y=60$, then $x=-40$ since $x+y=20$. However, substituting these values for $x$ and $y$ in the second equation yields $220=85$, which is a false statement.

Choice D is incorrect. If $y=65$, then $x=-45$ since $x+y=20$. However, substituting these values for $x$ and $y$ in the second equation yields $235=85$, which is a false statement.