During volcanic eruptions, hydrogen sulfide gas is released and is oxidized by the oxygen in the air yielding sulfur dioxide gas and water vapour. Calculate the standard enthalpy change for this reaction given the following:

Question

3S(rhombic) + 2H2O(g) → 2H2S(g) + SO2(g)

ΔH° = 146.9 kJ
S(rhombic) + O2(g) → SO2(g)

ΔH° = –296.4 k

Answer 1

Reverse eqn 1 and add to 3x eqn 2. That gives you the equation you want. Then for dH, change the sign of eqn 1 and add to 3x dH for eqn 2.
By the way, you can't get what you want UNLESS you balance that equation you want.
2H2S + 3O2 ==> 2SO2 + 2H2O