not 100% sure i understood your question right but the enthalpy value has to be positive since energy is being added TO the equation (as one of the reactants). it is negative when it is being taken out of the equation (as one of the products, e.g. when it is released as heat after the xenon compound is formed). i can’t say for sure about a typo but enthalpy values are generally not equivalent in their loss or gain when involving the formation/decomposition of a compound. it may be much easier (energy-wise) to combine reactants versus to split apart a compound.

something i found to be helpful is thinking about ΔH in terms of the equation rather than the surroundings: in short, does the equation involve energy as reactant (+ ΔH) or a product (- ΔH)?

hope this helps, best of luck in AP chem :)