SAT Question ca9bb527: Systems of Linear Equations answer and explanation with Desmos solution

Choice B is correct. It's given by the second equation in the system that $y=19$. Substituting $19$ for $y$ in the first equation yields $19=4x-9$. Adding $9$ to both sides of this equation yields $28=4x$. Dividing both sides of this equation by $4$ yields $7=x$. Therefore, since $x=7$ and $y=19$, the solution $\left(x,y\right)$ to the given system of equations is $\left(7,19\right)$.