The average cost per hour is total cost divided by the number of hours:

Split the fraction into two parts:

So the equivalent expression is $\frac{18}{h}+12$.

Factor each part first:

So the expression becomes

Now cancel common factors of $(x+3)$ and $(x-3)$:

Therefore, for every value of $x$ where the original expression is defined, the equivalent expression is $1$. Note that the original expression is undefined at $x=3$ and $x=-3$, but that does not change the simplified form on its domain.

Since the point $(4,3)$ is on the graph of $y=\frac{k}{x-2}$, substitute $x=4$ and $y=3$ to find $k$:

So $k=6$. The function is therefore

Now substitute $x=1$:

So the $y$-coordinate is $-6$.

Use the table values to write two equations. Since $Q(2)=8$, we have

so $2a+b=8$. Since $Q(4)=4$, we have

so $4a+b=12$. Subtracting the first equation from the second gives $2a=4$, so $a=2$. Then $2a+b=8$ becomes $4+b=8$, so $b=4$. Now evaluate $Q(3)$:

So the correct answer is $5$.

Substitute $n=12$ into the model $c=\frac{48}{n}$:

So the cost per box is \4$.$