SAT Question f0773a55: Linear Functions answer and explanation with Desmos solution

Choice A is correct. It's given that the electrician charges a onetime fee plus an hourly rate. It's also given that the graph represents the total charge, in dollars, for $x$ hours of work. This graph shows a linear relationship in the xy-plane. Thus, the total charge $y$, in dollars, for $x$ hours of work can be represented as $y=mx+b$, where $m$ is the slope and $\left(0,b\right)$ is the y-intercept of the graph of the equation in the xy-plane. Since the given graph represents the total charge, in dollars, by an electrician for $x$ hours of work, it follows that its slope is $m$, or the electrician's hourly rate.