$$\begin{gathered} ∆{\mathrm{H}}^0 \mathrm{for} \mathrm{a} \mathrm{reaction} , \\ {\mathrm{F}}_2+2\mathrm{HCl}\to 2 \mathrm{HF} +{\mathrm{Cl}}_2 \mathrm{is} \mathrm{given} \mathrm{as} \\ -352.8 \mathrm{kJ}. ∆{{\mathrm{H}}_{\mathrm{f}}}^0 \mathrm{for} \mathrm{HF} \mathrm{is} -268.3\mathrm{KJ} {\mathrm{mol}}^{-1}, \mathrm{then} \\ \mathrm{calculate} ∆{{\mathrm{H}}_{\mathrm{f}}}^0\left(\mathrm{kJ}/\mathrm{mol}\right) \mathrm{of} \mathrm{HCl} \end{gathered}$$

is -x then what is the value of x?