SAT Question 868fc236: Linear Functions answer and explanation with Desmos solution

Choice B is correct. The relationship between $x$ food calories and $k$ kilojoules can be modeled as a proportional relationship. Let $(x_1,k_1)$ and $(x_2,k_2)$ represent the values in the first two rows in the table: $(4.0,16.7)$ and $(9.0,37.7)$. The rate of change, or $\frac{k_2-k_1}{x_2-x_1}$, is $\frac{21}{5}=4.2$; therefore, the equation that best represents the relationship between $x$ and $k$ is $k=4.2x$.