A function satisfies f(2) = 7, f(4) = 13, and f(6) = 19. Assuming this pattern is linear, what is f(8)?

The outputs increase by $6$ each time $x$ increases by $2$, so the slope is $\frac{6}{2}=3$. The next step adds another $6$ to $f(6)=19$, so $f(8)=19+6=25$, choice J. As a formula, $f(x)=3x+1$, and $f(8)=24+1=25$. Choice F ($22$) adds only $3$, which is the change per unit of $x$ rather than per step of $2$. Choice H ($28$) adds $9$. Choice G ($31$) adds $12$, doubling the step. Because the table's inputs go up by $2$, each step must add $6$.