The line passes through $(0,3)$ and $(4,11)$, so its slope is $\frac{11-3}{4-0}=2$. That means the height increases by $2$ for each increase of $1$ mile in $x$. Starting from $y=3$ when $x=0$, at $x=1$ the value of $y$ is $3+2=5$. So the correct answer is $5$.

First divide both sides of $5(x-2)=20$ by $5$ to get $x-2=4$. Then add $2$ to find $x=6$. Since the question asks for $x+1$, the value is $6+1=7$.

The line crosses the $y$-axis at $(0,6)$, so the $y$-intercept is $6$. Its slope is

In slope-intercept form, $y=mx+b$, so the equation is $y=-2x+6$.

The line crosses the $y$-axis at $(0,4)$, so its $y$-intercept is $4$. From $(0,4)$ to $(2,0)$, the change in $y$ is $0-4=-4$ and the change in $x$ is $2-0=2$, so the slope is $\frac{-4}{2}=-2$. Therefore, the equation is $y=-2x+4$.

The total cost is modeled by the system information $n+p=5$. Since a pen costs $2$, substitute $p=2$ into the equation to get $n+2=5$. That equation can be used to find the notebook cost.