SAT Question c8bf5313: Nonlinear Equations In One Variable And Systems Of Equations In Two Variables answer and explanation with Desmos solution

Choice D is correct. Since the graphs of the equations in the given system intersect at the point $\left(x,y\right)$, the point $\left(x,y\right)$ represents a solution to the given system of equations. The first equation of the given system of equations states that $x=8$. Substituting $8$ for $x$ in the second equation of the given system of equations yields $y=8^2+8$, or $y=72$. Therefore, the value of $y$ is $72$.