Answer: 375 kJ/mol
Explanation:
1) δh = -200 kj/mol means that the reaction is exothermic and the products of the forward reaction are 200 kJ/mol lower in the potential energy diagram.
2) The reverse reaction must compensate the 200 kJ/mol and go upper as much as the activation energy of the forward reaction.
You can see the attache diagram to verify that
Ea reverse = Ea forward + | δh |
Ea reverse = 175 kJ / mol + | -200 kJ/mol | = 175 kJ/mol + 200 kJ/mol = 375 kJ/mol, which is the answer.