SAT Question 68f343c9: Linear Functions answer and explanation with Desmos solution

Choice D is correct. It's given that $f(x)=x+6$. Substituting $2$ for $x$ in the function $f$ yields $f(2)=2+6$, or $f(2)=8$. It's also given that $g(x)=6x$. Substituting $2$ for $x$ in the function $g$ yields $g(2)=(6)(2)$, or $g\left(2\right)=12$. Substituting $8$ for $f(2)$ and $12$ for $g(2)$ in the expression $7f(2)-g(2)$ yields $7(8)-12$, or $44$. Therefore, the value of $7f(2)-g(2)$ is $44$.