For a reversible reaction A $$\rightleftharpoons$$ B, the $$\Delta H$$ forward reaction $$= 20$$ kJ mol$$^{-1}$$. The activation energy of the uncatalyzed forward reaction is $$300$$ kJ mol$$^{-1}$$. When the reaction is catalysed keeping the reactant concentration same, the rate of the catalysed forward reaction at $$27°$$C is found to be same as that of the uncatalyzed reaction at $$327°$$C. The activation energy of the catalysed backward reaction is _____ kJ mol$$^{-1}$$.