The reaction $A\to C$ has activation for the forward and the backward reaction has 25KJ and 32KJ respectively. The $\Delta$ H for the reaction is:

The activation energy of the reverse reaction is higher than that of the forward reaction.
Hence, the reaction is exothermic.
For the exothermic reaction, the enthalpy change of the reaction is equal to the difference between the activation energy of the forward reaction and the reverse reaction.
$\Delta H=25kJ-32kJ=-7kJ.$