For the gaseous reaction $\mathrm{K}+\mathrm{F}\to {\mathrm{K}}^{+}+{\mathrm{F}}^{-}, \mathrm{\Delta H}$ was calculated to be $18.4\mathrm{kcal}/\mathrm{mol}$ under conditions where the cations and anions were perverted from combining with each other. The ionisation enthalpy of $\mathrm{K}$ is $4.3\mathrm{eV}/\mathrm{atom}.$ What is the electron gain enthalpy of $\mathrm{F}$ (in $\mathrm{eV}$)? If your answer is $\mathrm{x}$ report it as $-2\mathrm{x}.$