Answer
$\Delta H = + 726.5 kJ $
Work Step by Step
Given the reaction :
CH3OH + 3/2 O2 --> CO2 + 2 H2O $\Delta H = -726.5 kJ $
In order to find the enthalpy change for the reverse reaction, we must multiply the enthalpy by -1
Therefore, the enthalpy would be $\Delta H = -726.5 * -1 = 726.5 kJ $