SAT Question 3d1070c9: Linear Functions answer and explanation with Desmos solution

Choice C is correct. It's given that the function $f$ is defined by $f\left(x\right)=25x+30$. Substituting $2$ for $x$ in this equation yields $f\left(2\right)=25\left(2\right)+30$, which is equivalent to $f\left(2\right)=50+30$, or $f\left(2\right)=80$. Therefore, the value of $f\left(x\right)$ is $80$ when $x=2$.