For a reversible reaction A`harr`B, the `DeltaH_("forward reaction")=20 kJ mol^(-1)`.The activation energy of the uncatalysed 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 uncatalysed reaction at `327^@`C.The activation energy of the catalysed backward reaction is_____________ kJ `mol^(-1)`