[Solution by Dr. Abubacker] $y_1=\frac{x_1P_1^0}{x_1P_1^0+x_2P_2^0}\Rightarrow\frac1{y_1}=1+\frac{P_2^0}{P_1^0}\left(\frac1{x_1}-1\right)$. Solving for $\frac1{x_1}$: $\frac1{x_1}=\frac{P_1^0}{P_2^0}\cdot\frac1{y_1}+\frac{P_2^0-P_1^0}{P_2^0}$. So the slope is $\frac{P_1^0}{P_2^0}$ and the intercept is $\frac{P_2^0-P_1^0}{P_2^0}$. Answer (2).