A vegetable fiber is traded in a competitive world market, and the world price is $\$ 9$ per pound. Unlimited quantities are available for import into the United States at this price. The U.S. domestic supply and demand for various price levels are shown as follows:
$$\begin{array}{|c|c|c|}
\hline \text { PRICE } & \begin{array}{c}
\text { U.S. SUPPLY } \\
\text { (MILION LBS) }
\end{array} & \begin{array}{c}
\text { U.S. DEMAND } \\
\text { (MILIION LBS) }
\end{array} \\
\hline 3 & 2 & 34 \\
\hline 6 & 4 & 28 \\
\hline 9 & 6 & 22 \\
\hline 12 & 8 & 16 \\
\hline 15 & 10 & 10 \\
\hline 18 & 12 & 4 \\
\hline
\end{array}$$
a. What is the equation for demand? What is the equation for supply?
b. At a price of $\$ 9,$ what is the price elasticity of demand? What is it at a price of $\$ 12 ?$
c. What is the price elasticity of supply at $\$ 9 ?$ At $\$ 12 ?$
d. In a free market, what will be the U.S. price and level of fiber imports?