The Decomposition of Dinitrogen Pentaoxide Has an Activation Energy of 102

The decomposition of dinitrogen pentaoxide has an activation energy of 102 kJ/mol and $\Delta$ H°_rxn = + 55 kJ/mol.What is the activation energy for the reverse reaction?

A) 27 kJ/mol
B) 47 kJ/mol
C) 55 kJ/mol
D) 102 kJ/mol
E) More information is needed,since this is a Hess' Law calculation.