Chapter 12, Problem 83QAP

At a certain temperature, the reaction

$\text{Xe}\left(g\right)+2{\text{F}}_2\left(g\right)\rightleftharpoons {\text{XeF}}_4\left(g\right)$gives a 50.0% yield of XeF₄, starting with $\text{Xe}\left(P_{\text{xe}}=0.20\text{atm}\right)$ and ${\text{F}}_2\left(P_{{\text{F}}_2}=0.40\text{atm}\right)$. Calculate K at this temperature. What must the initial pressure of F₂ be to convert 75.0% of the xenon to XeF₄?