$0\mathrm{.}334V_{r}3,(2)$ generates two arrays for $P_r$ when $T_r=0\mathrm{.}85$ and $T_r=1$ by defining a function for $P_r,$ and $(3)$ makes the plots of $P_r($y$-$axis$)$ versus $V_r($x$-$axis$)$ for $T_r=0\mathrm{.}85$ and $T_r=1$ in a graph. Add axis titles and legends. The range of $P_r$ and $V_r$ in the graph should be $0P_{r}2\mathrm{.}5$ and $0V_{r}3.$ The colors for the plots of $T_r=0\mathrm{.}85$ and $T_r=1$ are red and blue, respectively.